| /* |
| * Resizable virtual memory filesystem for Linux. |
| * |
| * Copyright (C) 2000 Linus Torvalds. |
| * 2000 Transmeta Corp. |
| * 2000-2001 Christoph Rohland |
| * 2000-2001 SAP AG |
| * 2002 Red Hat Inc. |
| * Copyright (C) 2002-2011 Hugh Dickins. |
| * Copyright (C) 2011 Google Inc. |
| * Copyright (C) 2002-2005 VERITAS Software Corporation. |
| * Copyright (C) 2004 Andi Kleen, SuSE Labs |
| * |
| * Extended attribute support for tmpfs: |
| * Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@lkcl.net> |
| * Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com> |
| * |
| * tiny-shmem: |
| * Copyright (c) 2004, 2008 Matt Mackall <mpm@selenic.com> |
| * |
| * This file is released under the GPL. |
| */ |
| |
| #include <linux/fs.h> |
| #include <linux/init.h> |
| #include <linux/vfs.h> |
| #include <linux/mount.h> |
| #include <linux/ramfs.h> |
| #include <linux/pagemap.h> |
| #include <linux/file.h> |
| #include <linux/mm.h> |
| #include <linux/random.h> |
| #include <linux/sched/signal.h> |
| #include <linux/export.h> |
| #include <linux/swap.h> |
| #include <linux/uio.h> |
| #include <linux/khugepaged.h> |
| #include <linux/hugetlb.h> |
| #include <linux/frontswap.h> |
| #include <linux/fs_parser.h> |
| #include <linux/swapfile.h> |
| |
| static struct vfsmount *shm_mnt; |
| |
| #ifdef CONFIG_SHMEM |
| /* |
| * This virtual memory filesystem is heavily based on the ramfs. It |
| * extends ramfs by the ability to use swap and honor resource limits |
| * which makes it a completely usable filesystem. |
| */ |
| |
| #include <linux/xattr.h> |
| #include <linux/exportfs.h> |
| #include <linux/posix_acl.h> |
| #include <linux/posix_acl_xattr.h> |
| #include <linux/mman.h> |
| #include <linux/string.h> |
| #include <linux/slab.h> |
| #include <linux/backing-dev.h> |
| #include <linux/shmem_fs.h> |
| #include <linux/writeback.h> |
| #include <linux/blkdev.h> |
| #include <linux/pagevec.h> |
| #include <linux/percpu_counter.h> |
| #include <linux/falloc.h> |
| #include <linux/splice.h> |
| #include <linux/security.h> |
| #include <linux/swapops.h> |
| #include <linux/mempolicy.h> |
| #include <linux/namei.h> |
| #include <linux/ctype.h> |
| #include <linux/migrate.h> |
| #include <linux/highmem.h> |
| #include <linux/seq_file.h> |
| #include <linux/magic.h> |
| #include <linux/syscalls.h> |
| #include <linux/fcntl.h> |
| #include <uapi/linux/memfd.h> |
| #include <linux/userfaultfd_k.h> |
| #include <linux/rmap.h> |
| #include <linux/uuid.h> |
| |
| #include <linux/uaccess.h> |
| |
| #include "internal.h" |
| |
| #define BLOCKS_PER_PAGE (PAGE_SIZE/512) |
| #define VM_ACCT(size) (PAGE_ALIGN(size) >> PAGE_SHIFT) |
| |
| /* Pretend that each entry is of this size in directory's i_size */ |
| #define BOGO_DIRENT_SIZE 20 |
| |
| /* Symlink up to this size is kmalloc'ed instead of using a swappable page */ |
| #define SHORT_SYMLINK_LEN 128 |
| |
| /* |
| * shmem_fallocate communicates with shmem_fault or shmem_writepage via |
| * inode->i_private (with i_rwsem making sure that it has only one user at |
| * a time): we would prefer not to enlarge the shmem inode just for that. |
| */ |
| struct shmem_falloc { |
| wait_queue_head_t *waitq; /* faults into hole wait for punch to end */ |
| pgoff_t start; /* start of range currently being fallocated */ |
| pgoff_t next; /* the next page offset to be fallocated */ |
| pgoff_t nr_falloced; /* how many new pages have been fallocated */ |
| pgoff_t nr_unswapped; /* how often writepage refused to swap out */ |
| }; |
| |
| struct shmem_options { |
| unsigned long long blocks; |
| unsigned long long inodes; |
| struct mempolicy *mpol; |
| kuid_t uid; |
| kgid_t gid; |
| umode_t mode; |
| bool full_inums; |
| int huge; |
| int seen; |
| #define SHMEM_SEEN_BLOCKS 1 |
| #define SHMEM_SEEN_INODES 2 |
| #define SHMEM_SEEN_HUGE 4 |
| #define SHMEM_SEEN_INUMS 8 |
| }; |
| |
| #ifdef CONFIG_TMPFS |
| static unsigned long shmem_default_max_blocks(void) |
| { |
| return totalram_pages() / 2; |
| } |
| |
| static unsigned long shmem_default_max_inodes(void) |
| { |
| unsigned long nr_pages = totalram_pages(); |
| |
| return min(nr_pages - totalhigh_pages(), nr_pages / 2); |
| } |
| #endif |
| |
| static int shmem_swapin_page(struct inode *inode, pgoff_t index, |
| struct page **pagep, enum sgp_type sgp, |
| gfp_t gfp, struct vm_area_struct *vma, |
| vm_fault_t *fault_type); |
| static int shmem_getpage_gfp(struct inode *inode, pgoff_t index, |
| struct page **pagep, enum sgp_type sgp, |
| gfp_t gfp, struct vm_area_struct *vma, |
| struct vm_fault *vmf, vm_fault_t *fault_type); |
| |
| int shmem_getpage(struct inode *inode, pgoff_t index, |
| struct page **pagep, enum sgp_type sgp) |
| { |
| return shmem_getpage_gfp(inode, index, pagep, sgp, |
| mapping_gfp_mask(inode->i_mapping), NULL, NULL, NULL); |
| } |
| |
| static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb) |
| { |
| return sb->s_fs_info; |
| } |
| |
| /* |
| * shmem_file_setup pre-accounts the whole fixed size of a VM object, |
| * for shared memory and for shared anonymous (/dev/zero) mappings |
| * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1), |
| * consistent with the pre-accounting of private mappings ... |
| */ |
| static inline int shmem_acct_size(unsigned long flags, loff_t size) |
| { |
| return (flags & VM_NORESERVE) ? |
| 0 : security_vm_enough_memory_mm(current->mm, VM_ACCT(size)); |
| } |
| |
| static inline void shmem_unacct_size(unsigned long flags, loff_t size) |
| { |
| if (!(flags & VM_NORESERVE)) |
| vm_unacct_memory(VM_ACCT(size)); |
| } |
| |
| static inline int shmem_reacct_size(unsigned long flags, |
| loff_t oldsize, loff_t newsize) |
| { |
| if (!(flags & VM_NORESERVE)) { |
| if (VM_ACCT(newsize) > VM_ACCT(oldsize)) |
| return security_vm_enough_memory_mm(current->mm, |
| VM_ACCT(newsize) - VM_ACCT(oldsize)); |
| else if (VM_ACCT(newsize) < VM_ACCT(oldsize)) |
| vm_unacct_memory(VM_ACCT(oldsize) - VM_ACCT(newsize)); |
| } |
| return 0; |
| } |
| |
| /* |
| * ... whereas tmpfs objects are accounted incrementally as |
| * pages are allocated, in order to allow large sparse files. |
| * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM, |
| * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM. |
| */ |
| static inline int shmem_acct_block(unsigned long flags, long pages) |
| { |
| if (!(flags & VM_NORESERVE)) |
| return 0; |
| |
| return security_vm_enough_memory_mm(current->mm, |
| pages * VM_ACCT(PAGE_SIZE)); |
| } |
| |
| static inline void shmem_unacct_blocks(unsigned long flags, long pages) |
| { |
| if (flags & VM_NORESERVE) |
| vm_unacct_memory(pages * VM_ACCT(PAGE_SIZE)); |
| } |
| |
| static inline bool shmem_inode_acct_block(struct inode *inode, long pages) |
| { |
| struct shmem_inode_info *info = SHMEM_I(inode); |
| struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); |
| |
| if (shmem_acct_block(info->flags, pages)) |
| return false; |
| |
| if (sbinfo->max_blocks) { |
| if (percpu_counter_compare(&sbinfo->used_blocks, |
| sbinfo->max_blocks - pages) > 0) |
| goto unacct; |
| percpu_counter_add(&sbinfo->used_blocks, pages); |
| } |
| |
| return true; |
| |
| unacct: |
| shmem_unacct_blocks(info->flags, pages); |
| return false; |
| } |
| |
| static inline void shmem_inode_unacct_blocks(struct inode *inode, long pages) |
| { |
| struct shmem_inode_info *info = SHMEM_I(inode); |
| struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); |
| |
| if (sbinfo->max_blocks) |
| percpu_counter_sub(&sbinfo->used_blocks, pages); |
| shmem_unacct_blocks(info->flags, pages); |
| } |
| |
| static const struct super_operations shmem_ops; |
| const struct address_space_operations shmem_aops; |
| static const struct file_operations shmem_file_operations; |
| static const struct inode_operations shmem_inode_operations; |
| static const struct inode_operations shmem_dir_inode_operations; |
| static const struct inode_operations shmem_special_inode_operations; |
| static const struct vm_operations_struct shmem_vm_ops; |
| static struct file_system_type shmem_fs_type; |
| |
| bool vma_is_shmem(struct vm_area_struct *vma) |
| { |
| return vma->vm_ops == &shmem_vm_ops; |
| } |
| |
| static LIST_HEAD(shmem_swaplist); |
| static DEFINE_MUTEX(shmem_swaplist_mutex); |
| |
| /* |
| * shmem_reserve_inode() performs bookkeeping to reserve a shmem inode, and |
| * produces a novel ino for the newly allocated inode. |
| * |
| * It may also be called when making a hard link to permit the space needed by |
| * each dentry. However, in that case, no new inode number is needed since that |
| * internally draws from another pool of inode numbers (currently global |
| * get_next_ino()). This case is indicated by passing NULL as inop. |
| */ |
| #define SHMEM_INO_BATCH 1024 |
| static int shmem_reserve_inode(struct super_block *sb, ino_t *inop) |
| { |
| struct shmem_sb_info *sbinfo = SHMEM_SB(sb); |
| ino_t ino; |
| |
| if (!(sb->s_flags & SB_KERNMOUNT)) { |
| raw_spin_lock(&sbinfo->stat_lock); |
| if (sbinfo->max_inodes) { |
| if (!sbinfo->free_inodes) { |
| raw_spin_unlock(&sbinfo->stat_lock); |
| return -ENOSPC; |
| } |
| sbinfo->free_inodes--; |
| } |
| if (inop) { |
| ino = sbinfo->next_ino++; |
| if (unlikely(is_zero_ino(ino))) |
| ino = sbinfo->next_ino++; |
| if (unlikely(!sbinfo->full_inums && |
| ino > UINT_MAX)) { |
| /* |
| * Emulate get_next_ino uint wraparound for |
| * compatibility |
| */ |
| if (IS_ENABLED(CONFIG_64BIT)) |
| pr_warn("%s: inode number overflow on device %d, consider using inode64 mount option\n", |
| __func__, MINOR(sb->s_dev)); |
| sbinfo->next_ino = 1; |
| ino = sbinfo->next_ino++; |
| } |
| *inop = ino; |
| } |
| raw_spin_unlock(&sbinfo->stat_lock); |
| } else if (inop) { |
| /* |
| * __shmem_file_setup, one of our callers, is lock-free: it |
| * doesn't hold stat_lock in shmem_reserve_inode since |
| * max_inodes is always 0, and is called from potentially |
| * unknown contexts. As such, use a per-cpu batched allocator |
| * which doesn't require the per-sb stat_lock unless we are at |
| * the batch boundary. |
| * |
| * We don't need to worry about inode{32,64} since SB_KERNMOUNT |
| * shmem mounts are not exposed to userspace, so we don't need |
| * to worry about things like glibc compatibility. |
| */ |
| ino_t *next_ino; |
| |
| next_ino = per_cpu_ptr(sbinfo->ino_batch, get_cpu()); |
| ino = *next_ino; |
| if (unlikely(ino % SHMEM_INO_BATCH == 0)) { |
| raw_spin_lock(&sbinfo->stat_lock); |
| ino = sbinfo->next_ino; |
| sbinfo->next_ino += SHMEM_INO_BATCH; |
| raw_spin_unlock(&sbinfo->stat_lock); |
| if (unlikely(is_zero_ino(ino))) |
| ino++; |
| } |
| *inop = ino; |
| *next_ino = ++ino; |
| put_cpu(); |
| } |
| |
| return 0; |
| } |
| |
| static void shmem_free_inode(struct super_block *sb) |
| { |
| struct shmem_sb_info *sbinfo = SHMEM_SB(sb); |
| if (sbinfo->max_inodes) { |
| raw_spin_lock(&sbinfo->stat_lock); |
| sbinfo->free_inodes++; |
| raw_spin_unlock(&sbinfo->stat_lock); |
| } |
| } |
| |
| /** |
| * shmem_recalc_inode - recalculate the block usage of an inode |
| * @inode: inode to recalc |
| * |
| * We have to calculate the free blocks since the mm can drop |
| * undirtied hole pages behind our back. |
| * |
| * But normally info->alloced == inode->i_mapping->nrpages + info->swapped |
| * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped) |
| * |
| * It has to be called with the spinlock held. |
| */ |
| static void shmem_recalc_inode(struct inode *inode) |
| { |
| struct shmem_inode_info *info = SHMEM_I(inode); |
| long freed; |
| |
| freed = info->alloced - info->swapped - inode->i_mapping->nrpages; |
| if (freed > 0) { |
| info->alloced -= freed; |
| inode->i_blocks -= freed * BLOCKS_PER_PAGE; |
| shmem_inode_unacct_blocks(inode, freed); |
| } |
| } |
| |
| bool shmem_charge(struct inode *inode, long pages) |
| { |
| struct shmem_inode_info *info = SHMEM_I(inode); |
| unsigned long flags; |
| |
| if (!shmem_inode_acct_block(inode, pages)) |
| return false; |
| |
| /* nrpages adjustment first, then shmem_recalc_inode() when balanced */ |
| inode->i_mapping->nrpages += pages; |
| |
| spin_lock_irqsave(&info->lock, flags); |
| info->alloced += pages; |
| inode->i_blocks += pages * BLOCKS_PER_PAGE; |
| shmem_recalc_inode(inode); |
| spin_unlock_irqrestore(&info->lock, flags); |
| |
| return true; |
| } |
| |
| void shmem_uncharge(struct inode *inode, long pages) |
| { |
| struct shmem_inode_info *info = SHMEM_I(inode); |
| unsigned long flags; |
| |
| /* nrpages adjustment done by __delete_from_page_cache() or caller */ |
| |
| spin_lock_irqsave(&info->lock, flags); |
| info->alloced -= pages; |
| inode->i_blocks -= pages * BLOCKS_PER_PAGE; |
| shmem_recalc_inode(inode); |
| spin_unlock_irqrestore(&info->lock, flags); |
| |
| shmem_inode_unacct_blocks(inode, pages); |
| } |
| |
| /* |
| * Replace item expected in xarray by a new item, while holding xa_lock. |
| */ |
| static int shmem_replace_entry(struct address_space *mapping, |
| pgoff_t index, void *expected, void *replacement) |
| { |
| XA_STATE(xas, &mapping->i_pages, index); |
| void *item; |
| |
| VM_BUG_ON(!expected); |
| VM_BUG_ON(!replacement); |
| item = xas_load(&xas); |
| if (item != expected) |
| return -ENOENT; |
| xas_store(&xas, replacement); |
| return 0; |
| } |
| |
| /* |
| * Sometimes, before we decide whether to proceed or to fail, we must check |
| * that an entry was not already brought back from swap by a racing thread. |
| * |
| * Checking page is not enough: by the time a SwapCache page is locked, it |
| * might be reused, and again be SwapCache, using the same swap as before. |
| */ |
| static bool shmem_confirm_swap(struct address_space *mapping, |
| pgoff_t index, swp_entry_t swap) |
| { |
| return xa_load(&mapping->i_pages, index) == swp_to_radix_entry(swap); |
| } |
| |
| /* |
| * Definitions for "huge tmpfs": tmpfs mounted with the huge= option |
| * |
| * SHMEM_HUGE_NEVER: |
| * disables huge pages for the mount; |
| * SHMEM_HUGE_ALWAYS: |
| * enables huge pages for the mount; |
| * SHMEM_HUGE_WITHIN_SIZE: |
| * only allocate huge pages if the page will be fully within i_size, |
| * also respect fadvise()/madvise() hints; |
| * SHMEM_HUGE_ADVISE: |
| * only allocate huge pages if requested with fadvise()/madvise(); |
| */ |
| |
| #define SHMEM_HUGE_NEVER 0 |
| #define SHMEM_HUGE_ALWAYS 1 |
| #define SHMEM_HUGE_WITHIN_SIZE 2 |
| #define SHMEM_HUGE_ADVISE 3 |
| |
| /* |
| * Special values. |
| * Only can be set via /sys/kernel/mm/transparent_hugepage/shmem_enabled: |
| * |
| * SHMEM_HUGE_DENY: |
| * disables huge on shm_mnt and all mounts, for emergency use; |
| * SHMEM_HUGE_FORCE: |
| * enables huge on shm_mnt and all mounts, w/o needing option, for testing; |
| * |
| */ |
| #define SHMEM_HUGE_DENY (-1) |
| #define SHMEM_HUGE_FORCE (-2) |
| |
| #ifdef CONFIG_TRANSPARENT_HUGEPAGE |
| /* ifdef here to avoid bloating shmem.o when not necessary */ |
| |
| static int shmem_huge __read_mostly = SHMEM_HUGE_NEVER; |
| |
| bool shmem_is_huge(struct vm_area_struct *vma, |
| struct inode *inode, pgoff_t index) |
| { |
| loff_t i_size; |
| |
| if (shmem_huge == SHMEM_HUGE_DENY) |
| return false; |
| if (vma && ((vma->vm_flags & VM_NOHUGEPAGE) || |
| test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags))) |
| return false; |
| if (shmem_huge == SHMEM_HUGE_FORCE) |
| return true; |
| |
| switch (SHMEM_SB(inode->i_sb)->huge) { |
| case SHMEM_HUGE_ALWAYS: |
| return true; |
| case SHMEM_HUGE_WITHIN_SIZE: |
| index = round_up(index, HPAGE_PMD_NR); |
| i_size = round_up(i_size_read(inode), PAGE_SIZE); |
| if (i_size >= HPAGE_PMD_SIZE && (i_size >> PAGE_SHIFT) >= index) |
| return true; |
| fallthrough; |
| case SHMEM_HUGE_ADVISE: |
| if (vma && (vma->vm_flags & VM_HUGEPAGE)) |
| return true; |
| fallthrough; |
| default: |
| return false; |
| } |
| } |
| |
| #if defined(CONFIG_SYSFS) |
| static int shmem_parse_huge(const char *str) |
| { |
| if (!strcmp(str, "never")) |
| return SHMEM_HUGE_NEVER; |
| if (!strcmp(str, "always")) |
| return SHMEM_HUGE_ALWAYS; |
| if (!strcmp(str, "within_size")) |
| return SHMEM_HUGE_WITHIN_SIZE; |
| if (!strcmp(str, "advise")) |
| return SHMEM_HUGE_ADVISE; |
| if (!strcmp(str, "deny")) |
| return SHMEM_HUGE_DENY; |
| if (!strcmp(str, "force")) |
| return SHMEM_HUGE_FORCE; |
| return -EINVAL; |
| } |
| #endif |
| |
| #if defined(CONFIG_SYSFS) || defined(CONFIG_TMPFS) |
| static const char *shmem_format_huge(int huge) |
| { |
| switch (huge) { |
| case SHMEM_HUGE_NEVER: |
| return "never"; |
| case SHMEM_HUGE_ALWAYS: |
| return "always"; |
| case SHMEM_HUGE_WITHIN_SIZE: |
| return "within_size"; |
| case SHMEM_HUGE_ADVISE: |
| return "advise"; |
| case SHMEM_HUGE_DENY: |
| return "deny"; |
| case SHMEM_HUGE_FORCE: |
| return "force"; |
| default: |
| VM_BUG_ON(1); |
| return "bad_val"; |
| } |
| } |
| #endif |
| |
| static unsigned long shmem_unused_huge_shrink(struct shmem_sb_info *sbinfo, |
| struct shrink_control *sc, unsigned long nr_to_split) |
| { |
| LIST_HEAD(list), *pos, *next; |
| LIST_HEAD(to_remove); |
| struct inode *inode; |
| struct shmem_inode_info *info; |
| struct page *page; |
| unsigned long batch = sc ? sc->nr_to_scan : 128; |
| int removed = 0, split = 0; |
| |
| if (list_empty(&sbinfo->shrinklist)) |
| return SHRINK_STOP; |
| |
| spin_lock(&sbinfo->shrinklist_lock); |
| list_for_each_safe(pos, next, &sbinfo->shrinklist) { |
| info = list_entry(pos, struct shmem_inode_info, shrinklist); |
| |
| /* pin the inode */ |
| inode = igrab(&info->vfs_inode); |
| |
| /* inode is about to be evicted */ |
| if (!inode) { |
| list_del_init(&info->shrinklist); |
| removed++; |
| goto next; |
| } |
| |
| /* Check if there's anything to gain */ |
| if (round_up(inode->i_size, PAGE_SIZE) == |
| round_up(inode->i_size, HPAGE_PMD_SIZE)) { |
| list_move(&info->shrinklist, &to_remove); |
| removed++; |
| goto next; |
| } |
| |
| list_move(&info->shrinklist, &list); |
| next: |
| if (!--batch) |
| break; |
| } |
| spin_unlock(&sbinfo->shrinklist_lock); |
| |
| list_for_each_safe(pos, next, &to_remove) { |
| info = list_entry(pos, struct shmem_inode_info, shrinklist); |
| inode = &info->vfs_inode; |
| list_del_init(&info->shrinklist); |
| iput(inode); |
| } |
| |
| list_for_each_safe(pos, next, &list) { |
| int ret; |
| |
| info = list_entry(pos, struct shmem_inode_info, shrinklist); |
| inode = &info->vfs_inode; |
| |
| if (nr_to_split && split >= nr_to_split) |
| goto leave; |
| |
| page = find_get_page(inode->i_mapping, |
| (inode->i_size & HPAGE_PMD_MASK) >> PAGE_SHIFT); |
| if (!page) |
| goto drop; |
| |
| /* No huge page at the end of the file: nothing to split */ |
| if (!PageTransHuge(page)) { |
| put_page(page); |
| goto drop; |
| } |
| |
| /* |
| * Leave the inode on the list if we failed to lock |
| * the page at this time. |
| * |
| * Waiting for the lock may lead to deadlock in the |
| * reclaim path. |
| */ |
| if (!trylock_page(page)) { |
| put_page(page); |
| goto leave; |
| } |
| |
| ret = split_huge_page(page); |
| unlock_page(page); |
| put_page(page); |
| |
| /* If split failed leave the inode on the list */ |
| if (ret) |
| goto leave; |
| |
| split++; |
| drop: |
| list_del_init(&info->shrinklist); |
| removed++; |
| leave: |
| iput(inode); |
| } |
| |
| spin_lock(&sbinfo->shrinklist_lock); |
| list_splice_tail(&list, &sbinfo->shrinklist); |
| sbinfo->shrinklist_len -= removed; |
| spin_unlock(&sbinfo->shrinklist_lock); |
| |
| return split; |
| } |
| |
| static long shmem_unused_huge_scan(struct super_block *sb, |
| struct shrink_control *sc) |
| { |
| struct shmem_sb_info *sbinfo = SHMEM_SB(sb); |
| |
| if (!READ_ONCE(sbinfo->shrinklist_len)) |
| return SHRINK_STOP; |
| |
| return shmem_unused_huge_shrink(sbinfo, sc, 0); |
| } |
| |
| static long shmem_unused_huge_count(struct super_block *sb, |
| struct shrink_control *sc) |
| { |
| struct shmem_sb_info *sbinfo = SHMEM_SB(sb); |
| return READ_ONCE(sbinfo->shrinklist_len); |
| } |
| #else /* !CONFIG_TRANSPARENT_HUGEPAGE */ |
| |
| #define shmem_huge SHMEM_HUGE_DENY |
| |
| bool shmem_is_huge(struct vm_area_struct *vma, |
| struct inode *inode, pgoff_t index) |
| { |
| return false; |
| } |
| |
| static unsigned long shmem_unused_huge_shrink(struct shmem_sb_info *sbinfo, |
| struct shrink_control *sc, unsigned long nr_to_split) |
| { |
| return 0; |
| } |
| #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ |
| |
| /* |
| * Like add_to_page_cache_locked, but error if expected item has gone. |
| */ |
| static int shmem_add_to_page_cache(struct page *page, |
| struct address_space *mapping, |
| pgoff_t index, void *expected, gfp_t gfp, |
| struct mm_struct *charge_mm) |
| { |
| XA_STATE_ORDER(xas, &mapping->i_pages, index, compound_order(page)); |
| unsigned long i = 0; |
| unsigned long nr = compound_nr(page); |
| int error; |
| |
| VM_BUG_ON_PAGE(PageTail(page), page); |
| VM_BUG_ON_PAGE(index != round_down(index, nr), page); |
| VM_BUG_ON_PAGE(!PageLocked(page), page); |
| VM_BUG_ON_PAGE(!PageSwapBacked(page), page); |
| VM_BUG_ON(expected && PageTransHuge(page)); |
| |
| page_ref_add(page, nr); |
| page->mapping = mapping; |
| page->index = index; |
| |
| if (!PageSwapCache(page)) { |
| error = mem_cgroup_charge(page, charge_mm, gfp); |
| if (error) { |
| if (PageTransHuge(page)) { |
| count_vm_event(THP_FILE_FALLBACK); |
| count_vm_event(THP_FILE_FALLBACK_CHARGE); |
| } |
| goto error; |
| } |
| } |
| cgroup_throttle_swaprate(page, gfp); |
| |
| do { |
| void *entry; |
| xas_lock_irq(&xas); |
| entry = xas_find_conflict(&xas); |
| if (entry != expected) |
| xas_set_err(&xas, -EEXIST); |
| xas_create_range(&xas); |
| if (xas_error(&xas)) |
| goto unlock; |
| next: |
| xas_store(&xas, page); |
| if (++i < nr) { |
| xas_next(&xas); |
| goto next; |
| } |
| if (PageTransHuge(page)) { |
| count_vm_event(THP_FILE_ALLOC); |
| __mod_lruvec_page_state(page, NR_SHMEM_THPS, nr); |
| } |
| mapping->nrpages += nr; |
| __mod_lruvec_page_state(page, NR_FILE_PAGES, nr); |
| __mod_lruvec_page_state(page, NR_SHMEM, nr); |
| unlock: |
| xas_unlock_irq(&xas); |
| } while (xas_nomem(&xas, gfp)); |
| |
| if (xas_error(&xas)) { |
| error = xas_error(&xas); |
| goto error; |
| } |
| |
| return 0; |
| error: |
| page->mapping = NULL; |
| page_ref_sub(page, nr); |
| return error; |
| } |
| |
| /* |
| * Like delete_from_page_cache, but substitutes swap for page. |
| */ |
| static void shmem_delete_from_page_cache(struct page *page, void *radswap) |
| { |
| struct address_space *mapping = page->mapping; |
| int error; |
| |
| VM_BUG_ON_PAGE(PageCompound(page), page); |
| |
| xa_lock_irq(&mapping->i_pages); |
| error = shmem_replace_entry(mapping, page->index, page, radswap); |
| page->mapping = NULL; |
| mapping->nrpages--; |
| __dec_lruvec_page_state(page, NR_FILE_PAGES); |
| __dec_lruvec_page_state(page, NR_SHMEM); |
| xa_unlock_irq(&mapping->i_pages); |
| put_page(page); |
| BUG_ON(error); |
| } |
| |
| /* |
| * Remove swap entry from page cache, free the swap and its page cache. |
| */ |
| static int shmem_free_swap(struct address_space *mapping, |
| pgoff_t index, void *radswap) |
| { |
| void *old; |
| |
| old = xa_cmpxchg_irq(&mapping->i_pages, index, radswap, NULL, 0); |
| if (old != radswap) |
| return -ENOENT; |
| free_swap_and_cache(radix_to_swp_entry(radswap)); |
| return 0; |
| } |
| |
| /* |
| * Determine (in bytes) how many of the shmem object's pages mapped by the |
| * given offsets are swapped out. |
| * |
| * This is safe to call without i_rwsem or the i_pages lock thanks to RCU, |
| * as long as the inode doesn't go away and racy results are not a problem. |
| */ |
| unsigned long shmem_partial_swap_usage(struct address_space *mapping, |
| pgoff_t start, pgoff_t end) |
| { |
| XA_STATE(xas, &mapping->i_pages, start); |
| struct page *page; |
| unsigned long swapped = 0; |
| |
| rcu_read_lock(); |
| xas_for_each(&xas, page, end - 1) { |
| if (xas_retry(&xas, page)) |
| continue; |
| if (xa_is_value(page)) |
| swapped++; |
| |
| if (need_resched()) { |
| xas_pause(&xas); |
| cond_resched_rcu(); |
| } |
| } |
| |
| rcu_read_unlock(); |
| |
| return swapped << PAGE_SHIFT; |
| } |
| |
| /* |
| * Determine (in bytes) how many of the shmem object's pages mapped by the |
| * given vma is swapped out. |
| * |
| * This is safe to call without i_rwsem or the i_pages lock thanks to RCU, |
| * as long as the inode doesn't go away and racy results are not a problem. |
| */ |
| unsigned long shmem_swap_usage(struct vm_area_struct *vma) |
| { |
| struct inode *inode = file_inode(vma->vm_file); |
| struct shmem_inode_info *info = SHMEM_I(inode); |
| struct address_space *mapping = inode->i_mapping; |
| unsigned long swapped; |
| |
| /* Be careful as we don't hold info->lock */ |
| swapped = READ_ONCE(info->swapped); |
| |
| /* |
| * The easier cases are when the shmem object has nothing in swap, or |
| * the vma maps it whole. Then we can simply use the stats that we |
| * already track. |
| */ |
| if (!swapped) |
| return 0; |
| |
| if (!vma->vm_pgoff && vma->vm_end - vma->vm_start >= inode->i_size) |
| return swapped << PAGE_SHIFT; |
| |
| /* Here comes the more involved part */ |
| return shmem_partial_swap_usage(mapping, |
| linear_page_index(vma, vma->vm_start), |
| linear_page_index(vma, vma->vm_end)); |
| } |
| |
| /* |
| * SysV IPC SHM_UNLOCK restore Unevictable pages to their evictable lists. |
| */ |
| void shmem_unlock_mapping(struct address_space *mapping) |
| { |
| struct pagevec pvec; |
| pgoff_t index = 0; |
| |
| pagevec_init(&pvec); |
| /* |
| * Minor point, but we might as well stop if someone else SHM_LOCKs it. |
| */ |
| while (!mapping_unevictable(mapping)) { |
| if (!pagevec_lookup(&pvec, mapping, &index)) |
| break; |
| check_move_unevictable_pages(&pvec); |
| pagevec_release(&pvec); |
| cond_resched(); |
| } |
| } |
| |
| /* |
| * Check whether a hole-punch or truncation needs to split a huge page, |
| * returning true if no split was required, or the split has been successful. |
| * |
| * Eviction (or truncation to 0 size) should never need to split a huge page; |
| * but in rare cases might do so, if shmem_undo_range() failed to trylock on |
| * head, and then succeeded to trylock on tail. |
| * |
| * A split can only succeed when there are no additional references on the |
| * huge page: so the split below relies upon find_get_entries() having stopped |
| * when it found a subpage of the huge page, without getting further references. |
| */ |
| static bool shmem_punch_compound(struct page *page, pgoff_t start, pgoff_t end) |
| { |
| if (!PageTransCompound(page)) |
| return true; |
| |
| /* Just proceed to delete a huge page wholly within the range punched */ |
| if (PageHead(page) && |
| page->index >= start && page->index + HPAGE_PMD_NR <= end) |
| return true; |
| |
| /* Try to split huge page, so we can truly punch the hole or truncate */ |
| return split_huge_page(page) >= 0; |
| } |
| |
| /* |
| * Remove range of pages and swap entries from page cache, and free them. |
| * If !unfalloc, truncate or punch hole; if unfalloc, undo failed fallocate. |
| */ |
| static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend, |
| bool unfalloc) |
| { |
| struct address_space *mapping = inode->i_mapping; |
| struct shmem_inode_info *info = SHMEM_I(inode); |
| pgoff_t start = (lstart + PAGE_SIZE - 1) >> PAGE_SHIFT; |
| pgoff_t end = (lend + 1) >> PAGE_SHIFT; |
| unsigned int partial_start = lstart & (PAGE_SIZE - 1); |
| unsigned int partial_end = (lend + 1) & (PAGE_SIZE - 1); |
| struct pagevec pvec; |
| pgoff_t indices[PAGEVEC_SIZE]; |
| long nr_swaps_freed = 0; |
| pgoff_t index; |
| int i; |
| |
| if (lend == -1) |
| end = -1; /* unsigned, so actually very big */ |
| |
| if (info->fallocend > start && info->fallocend <= end && !unfalloc) |
| info->fallocend = start; |
| |
| pagevec_init(&pvec); |
| index = start; |
| while (index < end && find_lock_entries(mapping, index, end - 1, |
| &pvec, indices)) { |
| for (i = 0; i < pagevec_count(&pvec); i++) { |
| struct page *page = pvec.pages[i]; |
| |
| index = indices[i]; |
| |
| if (xa_is_value(page)) { |
| if (unfalloc) |
| continue; |
| nr_swaps_freed += !shmem_free_swap(mapping, |
| index, page); |
| continue; |
| } |
| index += thp_nr_pages(page) - 1; |
| |
| if (!unfalloc || !PageUptodate(page)) |
| truncate_inode_page(mapping, page); |
| unlock_page(page); |
| } |
| pagevec_remove_exceptionals(&pvec); |
| pagevec_release(&pvec); |
| cond_resched(); |
| index++; |
| } |
| |
| if (partial_start) { |
| struct page *page = NULL; |
| shmem_getpage(inode, start - 1, &page, SGP_READ); |
| if (page) { |
| unsigned int top = PAGE_SIZE; |
| if (start > end) { |
| top = partial_end; |
| partial_end = 0; |
| } |
| zero_user_segment(page, partial_start, top); |
| set_page_dirty(page); |
| unlock_page(page); |
| put_page(page); |
| } |
| } |
| if (partial_end) { |
| struct page *page = NULL; |
| shmem_getpage(inode, end, &page, SGP_READ); |
| if (page) { |
| zero_user_segment(page, 0, partial_end); |
| set_page_dirty(page); |
| unlock_page(page); |
| put_page(page); |
| } |
| } |
| if (start >= end) |
| return; |
| |
| index = start; |
| while (index < end) { |
| cond_resched(); |
| |
| if (!find_get_entries(mapping, index, end - 1, &pvec, |
| indices)) { |
| /* If all gone or hole-punch or unfalloc, we're done */ |
| if (index == start || end != -1) |
| break; |
| /* But if truncating, restart to make sure all gone */ |
| index = start; |
| continue; |
| } |
| for (i = 0; i < pagevec_count(&pvec); i++) { |
| struct page *page = pvec.pages[i]; |
| |
| index = indices[i]; |
| if (xa_is_value(page)) { |
| if (unfalloc) |
| continue; |
| if (shmem_free_swap(mapping, index, page)) { |
| /* Swap was replaced by page: retry */ |
| index--; |
| break; |
| } |
| nr_swaps_freed++; |
| continue; |
| } |
| |
| lock_page(page); |
| |
| if (!unfalloc || !PageUptodate(page)) { |
| if (page_mapping(page) != mapping) { |
| /* Page was replaced by swap: retry */ |
| unlock_page(page); |
| index--; |
| break; |
| } |
| VM_BUG_ON_PAGE(PageWriteback(page), page); |
| if (shmem_punch_compound(page, start, end)) |
| truncate_inode_page(mapping, page); |
| else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) { |
| /* Wipe the page and don't get stuck */ |
| clear_highpage(page); |
| flush_dcache_page(page); |
| set_page_dirty(page); |
| if (index < |
| round_up(start, HPAGE_PMD_NR)) |
| start = index + 1; |
| } |
| } |
| unlock_page(page); |
| } |
| pagevec_remove_exceptionals(&pvec); |
| pagevec_release(&pvec); |
| index++; |
| } |
| |
| spin_lock_irq(&info->lock); |
| info->swapped -= nr_swaps_freed; |
| shmem_recalc_inode(inode); |
| spin_unlock_irq(&info->lock); |
| } |
| |
| void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend) |
| { |
| shmem_undo_range(inode, lstart, lend, false); |
| inode->i_ctime = inode->i_mtime = current_time(inode); |
| } |
| EXPORT_SYMBOL_GPL(shmem_truncate_range); |
| |
| static int shmem_getattr(struct user_namespace *mnt_userns, |
| const struct path *path, struct kstat *stat, |
| u32 request_mask, unsigned int query_flags) |
| { |
| struct inode *inode = path->dentry->d_inode; |
| struct shmem_inode_info *info = SHMEM_I(inode); |
| |
| if (info->alloced - info->swapped != inode->i_mapping->nrpages) { |
| spin_lock_irq(&info->lock); |
| shmem_recalc_inode(inode); |
| spin_unlock_irq(&info->lock); |
| } |
| generic_fillattr(&init_user_ns, inode, stat); |
| |
| if (shmem_is_huge(NULL, inode, 0)) |
| stat->blksize = HPAGE_PMD_SIZE; |
| |
| return 0; |
| } |
| |
| static int shmem_setattr(struct user_namespace *mnt_userns, |
| struct dentry *dentry, struct iattr *attr) |
| { |
| struct inode *inode = d_inode(dentry); |
| struct shmem_inode_info *info = SHMEM_I(inode); |
| int error; |
| |
| error = setattr_prepare(&init_user_ns, dentry, attr); |
| if (error) |
| return error; |
| |
| if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) { |
| loff_t oldsize = inode->i_size; |
| loff_t newsize = attr->ia_size; |
| |
| /* protected by i_rwsem */ |
| if ((newsize < oldsize && (info->seals & F_SEAL_SHRINK)) || |
| (newsize > oldsize && (info->seals & F_SEAL_GROW))) |
| return -EPERM; |
| |
| if (newsize != oldsize) { |
| error = shmem_reacct_size(SHMEM_I(inode)->flags, |
| oldsize, newsize); |
| if (error) |
| return error; |
| i_size_write(inode, newsize); |
| inode->i_ctime = inode->i_mtime = current_time(inode); |
| } |
| if (newsize <= oldsize) { |
| loff_t holebegin = round_up(newsize, PAGE_SIZE); |
| if (oldsize > holebegin) |
| unmap_mapping_range(inode->i_mapping, |
| holebegin, 0, 1); |
| if (info->alloced) |
| shmem_truncate_range(inode, |
| newsize, (loff_t)-1); |
| /* unmap again to remove racily COWed private pages */ |
| if (oldsize > holebegin) |
| unmap_mapping_range(inode->i_mapping, |
| holebegin, 0, 1); |
| } |
| } |
| |
| setattr_copy(&init_user_ns, inode, attr); |
| if (attr->ia_valid & ATTR_MODE) |
| error = posix_acl_chmod(&init_user_ns, inode, inode->i_mode); |
| return error; |
| } |
| |
| static void shmem_evict_inode(struct inode *inode) |
| { |
| struct shmem_inode_info *info = SHMEM_I(inode); |
| struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); |
| |
| if (shmem_mapping(inode->i_mapping)) { |
| shmem_unacct_size(info->flags, inode->i_size); |
| inode->i_size = 0; |
| shmem_truncate_range(inode, 0, (loff_t)-1); |
| if (!list_empty(&info->shrinklist)) { |
| spin_lock(&sbinfo->shrinklist_lock); |
| if (!list_empty(&info->shrinklist)) { |
| list_del_init(&info->shrinklist); |
| sbinfo->shrinklist_len--; |
| } |
| spin_unlock(&sbinfo->shrinklist_lock); |
| } |
| while (!list_empty(&info->swaplist)) { |
| /* Wait while shmem_unuse() is scanning this inode... */ |
| wait_var_event(&info->stop_eviction, |
| !atomic_read(&info->stop_eviction)); |
| mutex_lock(&shmem_swaplist_mutex); |
| /* ...but beware of the race if we peeked too early */ |
| if (!atomic_read(&info->stop_eviction)) |
| list_del_init(&info->swaplist); |
| mutex_unlock(&shmem_swaplist_mutex); |
| } |
| } |
| |
| simple_xattrs_free(&info->xattrs); |
| WARN_ON(inode->i_blocks); |
| shmem_free_inode(inode->i_sb); |
| clear_inode(inode); |
| } |
| |
| static int shmem_find_swap_entries(struct address_space *mapping, |
| pgoff_t start, unsigned int nr_entries, |
| struct page **entries, pgoff_t *indices, |
| unsigned int type, bool frontswap) |
| { |
| XA_STATE(xas, &mapping->i_pages, start); |
| struct page *page; |
| swp_entry_t entry; |
| unsigned int ret = 0; |
| |
| if (!nr_entries) |
| return 0; |
| |
| rcu_read_lock(); |
| xas_for_each(&xas, page, ULONG_MAX) { |
| if (xas_retry(&xas, page)) |
| continue; |
| |
| if (!xa_is_value(page)) |
| continue; |
| |
| entry = radix_to_swp_entry(page); |
| if (swp_type(entry) != type) |
| continue; |
| if (frontswap && |
| !frontswap_test(swap_info[type], swp_offset(entry))) |
| continue; |
| |
| indices[ret] = xas.xa_index; |
| entries[ret] = page; |
| |
| if (need_resched()) { |
| xas_pause(&xas); |
| cond_resched_rcu(); |
| } |
| if (++ret == nr_entries) |
| break; |
| } |
| rcu_read_unlock(); |
| |
| return ret; |
| } |
| |
| /* |
| * Move the swapped pages for an inode to page cache. Returns the count |
| * of pages swapped in, or the error in case of failure. |
| */ |
| static int shmem_unuse_swap_entries(struct inode *inode, struct pagevec pvec, |
| pgoff_t *indices) |
| { |
| int i = 0; |
| int ret = 0; |
| int error = 0; |
| struct address_space *mapping = inode->i_mapping; |
| |
| for (i = 0; i < pvec.nr; i++) { |
| struct page *page = pvec.pages[i]; |
| |
| if (!xa_is_value(page)) |
| continue; |
| error = shmem_swapin_page(inode, indices[i], |
| &page, SGP_CACHE, |
| mapping_gfp_mask(mapping), |
| NULL, NULL); |
| if (error == 0) { |
| unlock_page(page); |
| put_page(page); |
| ret++; |
| } |
| if (error == -ENOMEM) |
| break; |
| error = 0; |
| } |
| return error ? error : ret; |
| } |
| |
| /* |
| * If swap found in inode, free it and move page from swapcache to filecache. |
| */ |
| static int shmem_unuse_inode(struct inode *inode, unsigned int type, |
| bool frontswap, unsigned long *fs_pages_to_unuse) |
| { |
| struct address_space *mapping = inode->i_mapping; |
| pgoff_t start = 0; |
| struct pagevec pvec; |
| pgoff_t indices[PAGEVEC_SIZE]; |
| bool frontswap_partial = (frontswap && *fs_pages_to_unuse > 0); |
| int ret = 0; |
| |
| pagevec_init(&pvec); |
| do { |
| unsigned int nr_entries = PAGEVEC_SIZE; |
| |
| if (frontswap_partial && *fs_pages_to_unuse < PAGEVEC_SIZE) |
| nr_entries = *fs_pages_to_unuse; |
| |
| pvec.nr = shmem_find_swap_entries(mapping, start, nr_entries, |
| pvec.pages, indices, |
| type, frontswap); |
| if (pvec.nr == 0) { |
| ret = 0; |
| break; |
| } |
| |
| ret = shmem_unuse_swap_entries(inode, pvec, indices); |
| if (ret < 0) |
| break; |
| |
| if (frontswap_partial) { |
| *fs_pages_to_unuse -= ret; |
| if (*fs_pages_to_unuse == 0) { |
| ret = FRONTSWAP_PAGES_UNUSED; |
| break; |
| } |
| } |
| |
| start = indices[pvec.nr - 1]; |
| } while (true); |
| |
| return ret; |
| } |
| |
| /* |
| * Read all the shared memory data that resides in the swap |
| * device 'type' back into memory, so the swap device can be |
| * unused. |
| */ |
| int shmem_unuse(unsigned int type, bool frontswap, |
| unsigned long *fs_pages_to_unuse) |
| { |
| struct shmem_inode_info *info, *next; |
| int error = 0; |
| |
| if (list_empty(&shmem_swaplist)) |
| return 0; |
| |
| mutex_lock(&shmem_swaplist_mutex); |
| list_for_each_entry_safe(info, next, &shmem_swaplist, swaplist) { |
| if (!info->swapped) { |
| list_del_init(&info->swaplist); |
| continue; |
| } |
| /* |
| * Drop the swaplist mutex while searching the inode for swap; |
| * but before doing so, make sure shmem_evict_inode() will not |
| * remove placeholder inode from swaplist, nor let it be freed |
| * (igrab() would protect from unlink, but not from unmount). |
| */ |
| atomic_inc(&info->stop_eviction); |
| mutex_unlock(&shmem_swaplist_mutex); |
| |
| error = shmem_unuse_inode(&info->vfs_inode, type, frontswap, |
| fs_pages_to_unuse); |
| cond_resched(); |
| |
| mutex_lock(&shmem_swaplist_mutex); |
| next = list_next_entry(info, swaplist); |
| if (!info->swapped) |
| list_del_init(&info->swaplist); |
| if (atomic_dec_and_test(&info->stop_eviction)) |
| wake_up_var(&info->stop_eviction); |
| if (error) |
| break; |
| } |
| mutex_unlock(&shmem_swaplist_mutex); |
| |
| return error; |
| } |
| |
| /* |
| * Move the page from the page cache to the swap cache. |
| */ |
| static int shmem_writepage(struct page *page, struct writeback_control *wbc) |
| { |
| struct shmem_inode_info *info; |
| struct address_space *mapping; |
| struct inode *inode; |
| swp_entry_t swap; |
| pgoff_t index; |
| |
| /* |
| * If /sys/kernel/mm/transparent_hugepage/shmem_enabled is "always" or |
| * "force", drivers/gpu/drm/i915/gem/i915_gem_shmem.c gets huge pages, |
| * and its shmem_writeback() needs them to be split when swapping. |
| */ |
| if (PageTransCompound(page)) { |
| /* Ensure the subpages are still dirty */ |
| SetPageDirty(page); |
| if (split_huge_page(page) < 0) |
| goto redirty; |
| ClearPageDirty(page); |
| } |
| |
| BUG_ON(!PageLocked(page)); |
| mapping = page->mapping; |
| index = page->index; |
| inode = mapping->host; |
| info = SHMEM_I(inode); |
| if (info->flags & VM_LOCKED) |
| goto redirty; |
| if (!total_swap_pages) |
| goto redirty; |
| |
| /* |
| * Our capabilities prevent regular writeback or sync from ever calling |
| * shmem_writepage; but a stacking filesystem might use ->writepage of |
| * its underlying filesystem, in which case tmpfs should write out to |
| * swap only in response to memory pressure, and not for the writeback |
| * threads or sync. |
| */ |
| if (!wbc->for_reclaim) { |
| WARN_ON_ONCE(1); /* Still happens? Tell us about it! */ |
| goto redirty; |
| } |
| |
| /* |
| * This is somewhat ridiculous, but without plumbing a SWAP_MAP_FALLOC |
| * value into swapfile.c, the only way we can correctly account for a |
| * fallocated page arriving here is now to initialize it and write it. |
| * |
| * That's okay for a page already fallocated earlier, but if we have |
| * not yet completed the fallocation, then (a) we want to keep track |
| * of this page in case we have to undo it, and (b) it may not be a |
| * good idea to continue anyway, once we're pushing into swap. So |
| * reactivate the page, and let shmem_fallocate() quit when too many. |
| */ |
| if (!PageUptodate(page)) { |
| if (inode->i_private) { |
| struct shmem_falloc *shmem_falloc; |
| spin_lock(&inode->i_lock); |
| shmem_falloc = inode->i_private; |
| if (shmem_falloc && |
| !shmem_falloc->waitq && |
| index >= shmem_falloc->start && |
| index < shmem_falloc->next) |
| shmem_falloc->nr_unswapped++; |
| else |
| shmem_falloc = NULL; |
| spin_unlock(&inode->i_lock); |
| if (shmem_falloc) |
| goto redirty; |
| } |
| clear_highpage(page); |
| flush_dcache_page(page); |
| SetPageUptodate(page); |
| } |
| |
| swap = get_swap_page(page); |
| if (!swap.val) |
| goto redirty; |
| |
| /* |
| * Add inode to shmem_unuse()'s list of swapped-out inodes, |
| * if it's not already there. Do it now before the page is |
| * moved to swap cache, when its pagelock no longer protects |
| * the inode from eviction. But don't unlock the mutex until |
| * we've incremented swapped, because shmem_unuse_inode() will |
| * prune a !swapped inode from the swaplist under this mutex. |
| */ |
| mutex_lock(&shmem_swaplist_mutex); |
| if (list_empty(&info->swaplist)) |
| list_add(&info->swaplist, &shmem_swaplist); |
| |
| if (add_to_swap_cache(page, swap, |
| __GFP_HIGH | __GFP_NOMEMALLOC | __GFP_NOWARN, |
| NULL) == 0) { |
| spin_lock_irq(&info->lock); |
| shmem_recalc_inode(inode); |
| info->swapped++; |
| spin_unlock_irq(&info->lock); |
| |
| swap_shmem_alloc(swap); |
| shmem_delete_from_page_cache(page, swp_to_radix_entry(swap)); |
| |
| mutex_unlock(&shmem_swaplist_mutex); |
| BUG_ON(page_mapped(page)); |
| swap_writepage(page, wbc); |
| return 0; |
| } |
| |
| mutex_unlock(&shmem_swaplist_mutex); |
| put_swap_page(page, swap); |
| redirty: |
| set_page_dirty(page); |
| if (wbc->for_reclaim) |
| return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */ |
| unlock_page(page); |
| return 0; |
| } |
| |
| #if defined(CONFIG_NUMA) && defined(CONFIG_TMPFS) |
| static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol) |
| { |
| char buffer[64]; |
| |
| if (!mpol || mpol->mode == MPOL_DEFAULT) |
| return; /* show nothing */ |
| |
| mpol_to_str(buffer, sizeof(buffer), mpol); |
| |
| seq_printf(seq, ",mpol=%s", buffer); |
| } |
| |
| static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo) |
| { |
| struct mempolicy *mpol = NULL; |
| if (sbinfo->mpol) { |
| raw_spin_lock(&sbinfo->stat_lock); /* prevent replace/use races */ |
| mpol = sbinfo->mpol; |
| mpol_get(mpol); |
| raw_spin_unlock(&sbinfo->stat_lock); |
| } |
| return mpol; |
| } |
| #else /* !CONFIG_NUMA || !CONFIG_TMPFS */ |
| static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol) |
| { |
| } |
| static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo) |
| { |
| return NULL; |
| } |
| #endif /* CONFIG_NUMA && CONFIG_TMPFS */ |
| #ifndef CONFIG_NUMA |
| #define vm_policy vm_private_data |
| #endif |
| |
| static void shmem_pseudo_vma_init(struct vm_area_struct *vma, |
| struct shmem_inode_info *info, pgoff_t index) |
| { |
| /* Create a pseudo vma that just contains the policy */ |
| vma_init(vma, NULL); |
| /* Bias interleave by inode number to distribute better across nodes */ |
| vma->vm_pgoff = index + info->vfs_inode.i_ino; |
| vma->vm_policy = mpol_shared_policy_lookup(&info->policy, index); |
| } |
| |
| static void shmem_pseudo_vma_destroy(struct vm_area_struct *vma) |
| { |
| /* Drop reference taken by mpol_shared_policy_lookup() */ |
| mpol_cond_put(vma->vm_policy); |
| } |
| |
| static struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp, |
| struct shmem_inode_info *info, pgoff_t index) |
| { |
| struct vm_area_struct pvma; |
| struct page *page; |
| struct vm_fault vmf = { |
| .vma = &pvma, |
| }; |
| |
| shmem_pseudo_vma_init(&pvma, info, index); |
| page = swap_cluster_readahead(swap, gfp, &vmf); |
| shmem_pseudo_vma_destroy(&pvma); |
| |
| return page; |
| } |
| |
| /* |
| * Make sure huge_gfp is always more limited than limit_gfp. |
| * Some of the flags set permissions, while others set limitations. |
| */ |
| static gfp_t limit_gfp_mask(gfp_t huge_gfp, gfp_t limit_gfp) |
| { |
| gfp_t allowflags = __GFP_IO | __GFP_FS | __GFP_RECLAIM; |
| gfp_t denyflags = __GFP_NOWARN | __GFP_NORETRY; |
| gfp_t zoneflags = limit_gfp & GFP_ZONEMASK; |
| gfp_t result = huge_gfp & ~(allowflags | GFP_ZONEMASK); |
| |
| /* Allow allocations only from the originally specified zones. */ |
| result |= zoneflags; |
| |
| /* |
| * Minimize the result gfp by taking the union with the deny flags, |
| * and the intersection of the allow flags. |
| */ |
| result |= (limit_gfp & denyflags); |
| result |= (huge_gfp & limit_gfp) & allowflags; |
| |
| return result; |
| } |
| |
| static struct page *shmem_alloc_hugepage(gfp_t gfp, |
| struct shmem_inode_info *info, pgoff_t index) |
| { |
| struct vm_area_struct pvma; |
| struct address_space *mapping = info->vfs_inode.i_mapping; |
| pgoff_t hindex; |
| struct page *page; |
| |
| hindex = round_down(index, HPAGE_PMD_NR); |
| if (xa_find(&mapping->i_pages, &hindex, hindex + HPAGE_PMD_NR - 1, |
| XA_PRESENT)) |
| return NULL; |
| |
| shmem_pseudo_vma_init(&pvma, info, hindex); |
| page = alloc_pages_vma(gfp, HPAGE_PMD_ORDER, &pvma, 0, numa_node_id(), |
| true); |
| shmem_pseudo_vma_destroy(&pvma); |
| if (page) |
| prep_transhuge_page(page); |
| else |
| count_vm_event(THP_FILE_FALLBACK); |
| return page; |
| } |
| |
| static struct page *shmem_alloc_page(gfp_t gfp, |
| struct shmem_inode_info *info, pgoff_t index) |
| { |
| struct vm_area_struct pvma; |
| struct page *page; |
| |
| shmem_pseudo_vma_init(&pvma, info, index); |
| page = alloc_page_vma(gfp, &pvma, 0); |
| shmem_pseudo_vma_destroy(&pvma); |
| |
| return page; |
| } |
| |
| static struct page *shmem_alloc_and_acct_page(gfp_t gfp, |
| struct inode *inode, |
| pgoff_t index, bool huge) |
| { |
| struct shmem_inode_info *info = SHMEM_I(inode); |
| struct page *page; |
| int nr; |
| int err = -ENOSPC; |
| |
| if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) |
| huge = false; |
| nr = huge ? HPAGE_PMD_NR : 1; |
| |
| if (!shmem_inode_acct_block(inode, nr)) |
| goto failed; |
| |
| if (huge) |
| page = shmem_alloc_hugepage(gfp, info, index); |
| else |
| page = shmem_alloc_page(gfp, info, index); |
| if (page) { |
| __SetPageLocked(page); |
| __SetPageSwapBacked(page); |
| return page; |
| } |
| |
| err = -ENOMEM; |
| shmem_inode_unacct_blocks(inode, nr); |
| failed: |
| return ERR_PTR(err); |
| } |
| |
| /* |
| * When a page is moved from swapcache to shmem filecache (either by the |
| * usual swapin of shmem_getpage_gfp(), or by the less common swapoff of |
| * shmem_unuse_inode()), it may have been read in earlier from swap, in |
| * ignorance of the mapping it belongs to. If that mapping has special |
| * constraints (like the gma500 GEM driver, which requires RAM below 4GB), |
| * we may need to copy to a suitable page before moving to filecache. |
| * |
| * In a future release, this may well be extended to respect cpuset and |
| * NUMA mempolicy, and applied also to anonymous pages in do_swap_page(); |
| * but for now it is a simple matter of zone. |
| */ |
| static bool shmem_should_replace_page(struct page *page, gfp_t gfp) |
| { |
| return page_zonenum(page) > gfp_zone(gfp); |
| } |
| |
| static int shmem_replace_page(struct page **pagep, gfp_t gfp, |
| struct shmem_inode_info *info, pgoff_t index) |
| { |
| struct page *oldpage, *newpage; |
| struct address_space *swap_mapping; |
| swp_entry_t entry; |
| pgoff_t swap_index; |
| int error; |
| |
| oldpage = *pagep; |
| entry.val = page_private(oldpage); |
| swap_index = swp_offset(entry); |
| swap_mapping = page_mapping(oldpage); |
| |
| /* |
| * We have arrived here because our zones are constrained, so don't |
| * limit chance of success by further cpuset and node constraints. |
| */ |
| gfp &= ~GFP_CONSTRAINT_MASK; |
| newpage = shmem_alloc_page(gfp, info, index); |
| if (!newpage) |
| return -ENOMEM; |
| |
| get_page(newpage); |
| copy_highpage(newpage, oldpage); |
| flush_dcache_page(newpage); |
| |
| __SetPageLocked(newpage); |
| __SetPageSwapBacked(newpage); |
| SetPageUptodate(newpage); |
| set_page_private(newpage, entry.val); |
| SetPageSwapCache(newpage); |
| |
| /* |
| * Our caller will very soon move newpage out of swapcache, but it's |
| * a nice clean interface for us to replace oldpage by newpage there. |
| */ |
| xa_lock_irq(&swap_mapping->i_pages); |
| error = shmem_replace_entry(swap_mapping, swap_index, oldpage, newpage); |
| if (!error) { |
| mem_cgroup_migrate(oldpage, newpage); |
| __inc_lruvec_page_state(newpage, NR_FILE_PAGES); |
| __dec_lruvec_page_state(oldpage, NR_FILE_PAGES); |
| } |
| xa_unlock_irq(&swap_mapping->i_pages); |
| |
| if (unlikely(error)) { |
| /* |
| * Is this possible? I think not, now that our callers check |
| * both PageSwapCache and page_private after getting page lock; |
| * but be defensive. Reverse old to newpage for clear and free. |
| */ |
| oldpage = newpage; |
| } else { |
| lru_cache_add(newpage); |
| *pagep = newpage; |
| } |
| |
| ClearPageSwapCache(oldpage); |
| set_page_private(oldpage, 0); |
| |
| unlock_page(oldpage); |
| put_page(oldpage); |
| put_page(oldpage); |
| return error; |
| } |
| |
| /* |
| * Swap in the page pointed to by *pagep. |
| * Caller has to make sure that *pagep contains a valid swapped page. |
| * Returns 0 and the page in pagep if success. On failure, returns the |
| * error code and NULL in *pagep. |
| */ |
| static int shmem_swapin_page(struct inode *inode, pgoff_t index, |
| struct page **pagep, enum sgp_type sgp, |
| gfp_t gfp, struct vm_area_struct *vma, |
| vm_fault_t *fault_type) |
| { |
| struct address_space *mapping = inode->i_mapping; |
| struct shmem_inode_info *info = SHMEM_I(inode); |
| struct mm_struct *charge_mm = vma ? vma->vm_mm : NULL; |
| struct page *page; |
| swp_entry_t swap; |
| int error; |
| |
| VM_BUG_ON(!*pagep || !xa_is_value(*pagep)); |
| swap = radix_to_swp_entry(*pagep); |
| *pagep = NULL; |
| |
| /* Look it up and read it in.. */ |
| page = lookup_swap_cache(swap, NULL, 0); |
| if (!page) { |
| /* Or update major stats only when swapin succeeds?? */ |
| if (fault_type) { |
| *fault_type |= VM_FAULT_MAJOR; |
| count_vm_event(PGMAJFAULT); |
| count_memcg_event_mm(charge_mm, PGMAJFAULT); |
| } |
| /* Here we actually start the io */ |
| page = shmem_swapin(swap, gfp, info, index); |
| if (!page) { |
| error = -ENOMEM; |
| goto failed; |
| } |
| } |
| |
| /* We have to do this with page locked to prevent races */ |
| lock_page(page); |
| if (!PageSwapCache(page) || page_private(page) != swap.val || |
| !shmem_confirm_swap(mapping, index, swap)) { |
| error = -EEXIST; |
| goto unlock; |
| } |
| if (!PageUptodate(page)) { |
| error = -EIO; |
| goto failed; |
| } |
| wait_on_page_writeback(page); |
| |
| /* |
| * Some architectures may have to restore extra metadata to the |
| * physical page after reading from swap. |
| */ |
| arch_swap_restore(swap, page); |
| |
| if (shmem_should_replace_page(page, gfp)) { |
| error = shmem_replace_page(&page, gfp, info, index); |
| if (error) |
| goto failed; |
| } |
| |
| error = shmem_add_to_page_cache(page, mapping, index, |
| swp_to_radix_entry(swap), gfp, |
| charge_mm); |
| if (error) |
| goto failed; |
| |
| spin_lock_irq(&info->lock); |
| info->swapped--; |
| shmem_recalc_inode(inode); |
| spin_unlock_irq(&info->lock); |
| |
| if (sgp == SGP_WRITE) |
| mark_page_accessed(page); |
| |
| delete_from_swap_cache(page); |
| set_page_dirty(page); |
| swap_free(swap); |
| |
| *pagep = page; |
| return 0; |
| failed: |
| if (!shmem_confirm_swap(mapping, index, swap)) |
| error = -EEXIST; |
| unlock: |
| if (page) { |
| unlock_page(page); |
| put_page(page); |
| } |
| |
| return error; |
| } |
| |
| /* |
| * shmem_getpage_gfp - find page in cache, or get from swap, or allocate |
| * |
| * If we allocate a new one we do not mark it dirty. That's up to the |
| * vm. If we swap it in we mark it dirty since we also free the swap |
| * entry since a page cannot live in both the swap and page cache. |
| * |
| * vma, vmf, and fault_type are only supplied by shmem_fault: |
| * otherwise they are NULL. |
| */ |
| static int shmem_getpage_gfp(struct inode *inode, pgoff_t index, |
| struct page **pagep, enum sgp_type sgp, gfp_t gfp, |
| struct vm_area_struct *vma, struct vm_fault *vmf, |
| vm_fault_t *fault_type) |
| { |
| struct address_space *mapping = inode->i_mapping; |
| struct shmem_inode_info *info = SHMEM_I(inode); |
| struct shmem_sb_info *sbinfo; |
| struct mm_struct *charge_mm; |
| struct page *page; |
| pgoff_t hindex = index; |
| gfp_t huge_gfp; |
| int error; |
| int once = 0; |
| int alloced = 0; |
| |
| if (index > (MAX_LFS_FILESIZE >> PAGE_SHIFT)) |
| return -EFBIG; |
| repeat: |
| if (sgp <= SGP_CACHE && |
| ((loff_t)index << PAGE_SHIFT) >= i_size_read(inode)) { |
| return -EINVAL; |
| } |
| |
| sbinfo = SHMEM_SB(inode->i_sb); |
| charge_mm = vma ? vma->vm_mm : NULL; |
| |
| page = pagecache_get_page(mapping, index, |
| FGP_ENTRY | FGP_HEAD | FGP_LOCK, 0); |
| |
| if (page && vma && userfaultfd_minor(vma)) { |
| if (!xa_is_value(page)) { |
| unlock_page(page); |
| put_page(page); |
| } |
| *fault_type = handle_userfault(vmf, VM_UFFD_MINOR); |
| return 0; |
| } |
| |
| if (xa_is_value(page)) { |
| error = shmem_swapin_page(inode, index, &page, |
| sgp, gfp, vma, fault_type); |
| if (error == -EEXIST) |
| goto repeat; |
| |
| *pagep = page; |
| return error; |
| } |
| |
| if (page) { |
| hindex = page->index; |
| if (sgp == SGP_WRITE) |
| mark_page_accessed(page); |
| if (PageUptodate(page)) |
| goto out; |
| /* fallocated page */ |
| if (sgp != SGP_READ) |
| goto clear; |
| unlock_page(page); |
| put_page(page); |
| } |
| |
| /* |
| * SGP_READ: succeed on hole, with NULL page, letting caller zero. |
| * SGP_NOALLOC: fail on hole, with NULL page, letting caller fail. |
| */ |
| *pagep = NULL; |
| if (sgp == SGP_READ) |
| return 0; |
| if (sgp == SGP_NOALLOC) |
| return -ENOENT; |
| |
| /* |
| * Fast cache lookup and swap lookup did not find it: allocate. |
| */ |
| |
| if (vma && userfaultfd_missing(vma)) { |
| *fault_type = handle_userfault(vmf, VM_UFFD_MISSING); |
| return 0; |
| } |
| |
| /* Never use a huge page for shmem_symlink() */ |
| if (S_ISLNK(inode->i_mode)) |
| goto alloc_nohuge; |
| if (!shmem_is_huge(vma, inode, index)) |
| goto alloc_nohuge; |
| |
| huge_gfp = vma_thp_gfp_mask(vma); |
| huge_gfp = limit_gfp_mask(huge_gfp, gfp); |
| page = shmem_alloc_and_acct_page(huge_gfp, inode, index, true); |
| if (IS_ERR(page)) { |
| alloc_nohuge: |
| page = shmem_alloc_and_acct_page(gfp, inode, |
| index, false); |
| } |
| if (IS_ERR(page)) { |
| int retry = 5; |
| |
| error = PTR_ERR(page); |
| page = NULL; |
| if (error != -ENOSPC) |
| goto unlock; |
| /* |
| * Try to reclaim some space by splitting a huge page |
| * beyond i_size on the filesystem. |
| */ |
| while (retry--) { |
| int ret; |
| |
| ret = shmem_unused_huge_shrink(sbinfo, NULL, 1); |
| if (ret == SHRINK_STOP) |
| break; |
| if (ret) |
| goto alloc_nohuge; |
| } |
| goto unlock; |
| } |
| |
| if (PageTransHuge(page)) |
| hindex = round_down(index, HPAGE_PMD_NR); |
| else |
| hindex = index; |
| |
| if (sgp == SGP_WRITE) |
| __SetPageReferenced(page); |
| |
| error = shmem_add_to_page_cache(page, mapping, hindex, |
| NULL, gfp & GFP_RECLAIM_MASK, |
| charge_mm); |
| if (error) |
| goto unacct; |
| lru_cache_add(page); |
| |
| spin_lock_irq(&info->lock); |
| info->alloced += compound_nr(page); |
| inode->i_blocks += BLOCKS_PER_PAGE << compound_order(page); |
| shmem_recalc_inode(inode); |
| spin_unlock_irq(&info->lock); |
| alloced = true; |
| |
| if (PageTransHuge(page) && |
| DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE) < |
| hindex + HPAGE_PMD_NR - 1) { |
| /* |
| * Part of the huge page is beyond i_size: subject |
| * to shrink under memory pressure. |
| */ |
| spin_lock(&sbinfo->shrinklist_lock); |
| /* |
| * _careful to defend against unlocked access to |
| * ->shrink_list in shmem_unused_huge_shrink() |
| */ |
| if (list_empty_careful(&info->shrinklist)) { |
| list_add_tail(&info->shrinklist, |
| &sbinfo->shrinklist); |
| sbinfo->shrinklist_len++; |
| } |
| spin_unlock(&sbinfo->shrinklist_lock); |
| } |
| |
| /* |
| * Let SGP_FALLOC use the SGP_WRITE optimization on a new page. |
| */ |
| if (sgp == SGP_FALLOC) |
| sgp = SGP_WRITE; |
| clear: |
| /* |
| * Let SGP_WRITE caller clear ends if write does not fill page; |
| * but SGP_FALLOC on a page fallocated earlier must initialize |
| * it now, lest undo on failure cancel our earlier guarantee. |
| */ |
| if (sgp != SGP_WRITE && !PageUptodate(page)) { |
| int i; |
| |
| for (i = 0; i < compound_nr(page); i++) { |
| clear_highpage(page + i); |
| flush_dcache_page(page + i); |
| } |
| SetPageUptodate(page); |
| } |
| |
| /* Perhaps the file has been truncated since we checked */ |
| if (sgp <= SGP_CACHE && |
| ((loff_t)index << PAGE_SHIFT) >= i_size_read(inode)) { |
| if (alloced) { |
| ClearPageDirty(page); |
| delete_from_page_cache(page); |
| spin_lock_irq(&info->lock); |
| shmem_recalc_inode(inode); |
| spin_unlock_irq(&info->lock); |
| } |
| error = -EINVAL; |
| goto unlock; |
| } |
| out: |
| *pagep = page + index - hindex; |
| return 0; |
| |
| /* |
| * Error recovery. |
| */ |
| unacct: |
| shmem_inode_unacct_blocks(inode, compound_nr(page)); |
| |
| if (PageTransHuge(page)) { |
| unlock_page(page); |
| put_page(page); |
| goto alloc_nohuge; |
| } |
| unlock: |
| if (page) { |
| unlock_page(page); |
| put_page(page); |
| } |
| if (error == -ENOSPC && !once++) { |
| spin_lock_irq(&info->lock); |
| shmem_recalc_inode(inode); |
| spin_unlock_irq(&info->lock); |
| goto repeat; |
| } |
| if (error == -EEXIST) |
| goto repeat; |
| return error; |
| } |
| |
| /* |
| * This is like autoremove_wake_function, but it removes the wait queue |
| * entry unconditionally - even if something else had already woken the |
| * target. |
| */ |
| static int synchronous_wake_function(wait_queue_entry_t *wait, unsigned mode, int sync, void *key) |
| { |
| int ret = default_wake_function(wait, mode, sync, key); |
| list_del_init(&wait->entry); |
| return ret; |
| } |
| |
| static vm_fault_t shmem_fault(struct vm_fault *vmf) |
| { |
| struct vm_area_struct *vma = vmf->vma; |
| struct inode *inode = file_inode(vma->vm_file); |
| gfp_t gfp = mapping_gfp_mask(inode->i_mapping); |
| int err; |
| vm_fault_t ret = VM_FAULT_LOCKED; |
| |
| /* |
| * Trinity finds that probing a hole which tmpfs is punching can |
| * prevent the hole-punch from ever completing: which in turn |
| * locks writers out with its hold on i_rwsem. So refrain from |
| * faulting pages into the hole while it's being punched. Although |
| * shmem_undo_range() does remove the additions, it may be unable to |
| * keep up, as each new page needs its own unmap_mapping_range() call, |
| * and the i_mmap tree grows ever slower to scan if new vmas are added. |
| * |
| * It does not matter if we sometimes reach this check just before the |
| * hole-punch begins, so that one fault then races with the punch: |
| * we just need to make racing faults a rare case. |
| * |
| * The implementation below would be much simpler if we just used a |
| * standard mutex or completion: but we cannot take i_rwsem in fault, |
| * and bloating every shmem inode for this unlikely case would be sad. |
| */ |
| if (unlikely(inode->i_private)) { |
| struct shmem_falloc *shmem_falloc; |
| |
| spin_lock(&inode->i_lock); |
| shmem_falloc = inode->i_private; |
| if (shmem_falloc && |
| shmem_falloc->waitq && |
| vmf->pgoff >= shmem_falloc->start && |
| vmf->pgoff < shmem_falloc->next) { |
| struct file *fpin; |
| wait_queue_head_t *shmem_falloc_waitq; |
| DEFINE_WAIT_FUNC(shmem_fault_wait, synchronous_wake_function); |
| |
| ret = VM_FAULT_NOPAGE; |
| fpin = maybe_unlock_mmap_for_io(vmf, NULL); |
| if (fpin) |
| ret = VM_FAULT_RETRY; |
| |
| shmem_falloc_waitq = shmem_falloc->waitq; |
| prepare_to_wait(shmem_falloc_waitq, &shmem_fault_wait, |
| TASK_UNINTERRUPTIBLE); |
| spin_unlock(&inode->i_lock); |
| schedule(); |
| |
| /* |
| * shmem_falloc_waitq points into the shmem_fallocate() |
| * stack of the hole-punching task: shmem_falloc_waitq |
| * is usually invalid by the time we reach here, but |
| * finish_wait() does not dereference it in that case; |
| * though i_lock needed lest racing with wake_up_all(). |
| */ |
| spin_lock(&inode->i_lock); |
| finish_wait(shmem_falloc_waitq, &shmem_fault_wait); |
| spin_unlock(&inode->i_lock); |
| |
| if (fpin) |
| fput(fpin); |
| return ret; |
| } |
| spin_unlock(&inode->i_lock); |
| } |
| |
| err = shmem_getpage_gfp(inode, vmf->pgoff, &vmf->page, SGP_CACHE, |
| gfp, vma, vmf, &ret); |
| if (err) |
| return vmf_error(err); |
| return ret; |
| } |
| |
| unsigned long shmem_get_unmapped_area(struct file *file, |
| unsigned long uaddr, unsigned long len, |
| unsigned long pgoff, unsigned long flags) |
| { |
| unsigned long (*get_area)(struct file *, |
| unsigned long, unsigned long, unsigned long, unsigned long); |
| unsigned long addr; |
| unsigned long offset; |
| unsigned long inflated_len; |
| unsigned long inflated_addr; |
| unsigned long inflated_offset; |
| |
| if (len > TASK_SIZE) |
| return -ENOMEM; |
| |
| get_area = current->mm->get_unmapped_area; |
| addr = get_area(file, uaddr, len, pgoff, flags); |
| |
| if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) |
| return addr; |
| if (IS_ERR_VALUE(addr)) |
| return addr; |
| if (addr & ~PAGE_MASK) |
| return addr; |
| if (addr > TASK_SIZE - len) |
| return addr; |
| |
| if (shmem_huge == SHMEM_HUGE_DENY) |
| return addr; |
| if (len < HPAGE_PMD_SIZE) |
| return addr; |
| if (flags & MAP_FIXED) |
| return addr; |
| /* |
| * Our priority is to support MAP_SHARED mapped hugely; |
| * and support MAP_PRIVATE mapped hugely too, until it is COWed. |
| * But if caller specified an address hint and we allocated area there |
| * successfully, respect that as before. |
| */ |
| if (uaddr == addr) |
| return addr; |
| |
| if (shmem_huge != SHMEM_HUGE_FORCE) { |
| struct super_block *sb; |
| |
| if (file) { |
| VM_BUG_ON(file->f_op != &shmem_file_operations); |
| sb = file_inode(file)->i_sb; |
| } else { |
| /* |
| * Called directly from mm/mmap.c, or drivers/char/mem.c |
| * for "/dev/zero", to create a shared anonymous object. |
| */ |
| if (IS_ERR(shm_mnt)) |
| return addr; |
| sb = shm_mnt->mnt_sb; |
| } |
| if (SHMEM_SB(sb)->huge == SHMEM_HUGE_NEVER) |
| return addr; |
| } |
| |
| offset = (pgoff << PAGE_SHIFT) & (HPAGE_PMD_SIZE-1); |
| if (offset && offset + len < 2 * HPAGE_PMD_SIZE) |
| return addr; |
| if ((addr & (HPAGE_PMD_SIZE-1)) == offset) |
| return addr; |
| |
| inflated_len = len + HPAGE_PMD_SIZE - PAGE_SIZE; |
| if (inflated_len > TASK_SIZE) |
| return addr; |
| if (inflated_len < len) |
| return addr; |
| |
| inflated_addr = get_area(NULL, uaddr, inflated_len, 0, flags); |
| if (IS_ERR_VALUE(inflated_addr)) |
| return addr; |
| if (inflated_addr & ~PAGE_MASK) |
| return addr; |
| |
| inflated_offset = inflated_addr & (HPAGE_PMD_SIZE-1); |
| inflated_addr += offset - inflated_offset; |
| if (inflated_offset > offset) |
| inflated_addr += HPAGE_PMD_SIZE; |
| |
| if (inflated_addr > TASK_SIZE - len) |
| return addr; |
| return inflated_addr; |
| } |
| |
| #ifdef CONFIG_NUMA |
| static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *mpol) |
| { |
| struct inode *inode = file_inode(vma->vm_file); |
| return mpol_set_shared_policy(&SHMEM_I(inode)->policy, vma, mpol); |
| } |
| |
| static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma, |
| unsigned long addr) |
| { |
| struct inode *inode = file_inode(vma->vm_file); |
| pgoff_t index; |
| |
| index = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; |
| return mpol_shared_policy_lookup(&SHMEM_I(inode)->policy, index); |
| } |
| #endif |
| |
| int shmem_lock(struct file *file, int lock, struct ucounts *ucounts) |
| { |
| struct inode *inode = file_inode(file); |
| struct shmem_inode_info *info = SHMEM_I(inode); |
| int retval = -ENOMEM; |
| |
| /* |
| * What serializes the accesses to info->flags? |
| * ipc_lock_object() when called from shmctl_do_lock(), |
| * no serialization needed when called from shm_destroy(). |
| */ |
| if (lock && !(info->flags & VM_LOCKED)) { |
| if (!user_shm_lock(inode->i_size, ucounts)) |
| goto out_nomem; |
| info->flags |= VM_LOCKED; |
| mapping_set_unevictable(file->f_mapping); |
| } |
| if (!lock && (info->flags & VM_LOCKED) && ucounts) { |
| user_shm_unlock(inode->i_size, ucounts); |
| info->flags &= ~VM_LOCKED; |
| mapping_clear_unevictable(file->f_mapping); |
| } |
| retval = 0; |
| |
| out_nomem: |
| return retval; |
| } |
| |
| static int shmem_mmap(struct file *file, struct vm_area_struct *vma) |
| { |
| struct shmem_inode_info *info = SHMEM_I(file_inode(file)); |
| int ret; |
| |
| ret = seal_check_future_write(info->seals, vma); |
| if (ret) |
| return ret; |
| |
| /* arm64 - allow memory tagging on RAM-based files */ |
| vma->vm_flags |= VM_MTE_ALLOWED; |
| |
| file_accessed(file); |
| vma->vm_ops = &shmem_vm_ops; |
| if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && |
| ((vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK) < |
| (vma->vm_end & HPAGE_PMD_MASK)) { |
| khugepaged_enter(vma, vma->vm_flags); |
| } |
| return 0; |
| } |
| |
| static struct inode *shmem_get_inode(struct super_block *sb, const struct inode *dir, |
| umode_t mode, dev_t dev, unsigned long flags) |
| { |
| struct inode *inode; |
| struct shmem_inode_info *info; |
| struct shmem_sb_info *sbinfo = SHMEM_SB(sb); |
| ino_t ino; |
| |
| if (shmem_reserve_inode(sb, &ino)) |
| return NULL; |
| |
| inode = new_inode(sb); |
| if (inode) { |
| inode->i_ino = ino; |
| inode_init_owner(&init_user_ns, inode, dir, mode); |
| inode->i_blocks = 0; |
| inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode); |
| inode->i_generation = prandom_u32(); |
| info = SHMEM_I(inode); |
| memset(info, 0, (char *)inode - (char *)info); |
| spin_lock_init(&info->lock); |
| atomic_set(&info->stop_eviction, 0); |
| info->seals = F_SEAL_SEAL; |
| info->flags = flags & VM_NORESERVE; |
| INIT_LIST_HEAD(&info->shrinklist); |
| INIT_LIST_HEAD(&info->swaplist); |
| simple_xattrs_init(&info->xattrs); |
| cache_no_acl(inode); |
| |
| switch (mode & S_IFMT) { |
| default: |
| inode->i_op = &shmem_special_inode_operations; |
| init_special_inode(inode, mode, dev); |
| break; |
| case S_IFREG: |
| inode->i_mapping->a_ops = &shmem_aops; |
| inode->i_op = &shmem_inode_operations; |
| inode->i_fop = &shmem_file_operations; |
| mpol_shared_policy_init(&info->policy, |
| shmem_get_sbmpol(sbinfo)); |
| break; |
| case S_IFDIR: |
| inc_nlink(inode); |
| /* Some things misbehave if size == 0 on a directory */ |
| inode->i_size = 2 * BOGO_DIRENT_SIZE; |
| inode->i_op = &shmem_dir_inode_operations; |
| inode->i_fop = &simple_dir_operations; |
| break; |
| case S_IFLNK: |
| /* |
| * Must not load anything in the rbtree, |
| * mpol_free_shared_policy will not be called. |
| */ |
| mpol_shared_policy_init(&info->policy, NULL); |
| break; |
| } |
| |
| lockdep_annotate_inode_mutex_key(inode); |
| } else |
| shmem_free_inode(sb); |
| return inode; |
| } |
| |
| #ifdef CONFIG_USERFAULTFD |
| int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, |
| pmd_t *dst_pmd, |
| struct vm_area_struct *dst_vma, |
| unsigned long dst_addr, |
| unsigned long src_addr, |
| bool zeropage, |
| struct page **pagep) |
| { |
| struct inode *inode = file_inode(dst_vma->vm_file); |
| struct shmem_inode_info *info = SHMEM_I(inode); |
| struct address_space *mapping = inode->i_mapping; |
| gfp_t gfp = mapping_gfp_mask(mapping); |
| pgoff_t pgoff = linear_page_index(dst_vma, dst_addr); |
| void *page_kaddr; |
| struct page *page; |
| int ret; |
| pgoff_t max_off; |
| |
| if (!shmem_inode_acct_block(inode, 1)) { |
| /* |
| * We may have got a page, returned -ENOENT triggering a retry, |
| * and now we find ourselves with -ENOMEM. Release the page, to |
| * avoid a BUG_ON in our caller. |
| */ |
| if (unlikely(*pagep)) { |
| put_page(*pagep); |
| *pagep = NULL; |
| } |
| return -ENOMEM; |
| } |
| |
| if (!*pagep) { |
| ret = -ENOMEM; |
| page = shmem_alloc_page(gfp, info, pgoff); |
| if (!page) |
| goto out_unacct_blocks; |
| |
| if (!zeropage) { /* COPY */ |
| page_kaddr = kmap_atomic(page); |
| ret = copy_from_user(page_kaddr, |
| (const void __user *)src_addr, |
| PAGE_SIZE); |
| kunmap_atomic(page_kaddr); |
| |
| /* fallback to copy_from_user outside mmap_lock */ |
| if (unlikely(ret)) { |
| *pagep = page; |
| ret = -ENOENT; |
| /* don't free the page */ |
| goto out_unacct_blocks; |
| } |
| } else { /* ZEROPAGE */ |
| clear_highpage(page); |
| } |
| } else { |
| page = *pagep; |
| *pagep = NULL; |
| } |
| |
| VM_BUG_ON(PageLocked(page)); |
| VM_BUG_ON(PageSwapBacked(page)); |
| __SetPageLocked(page); |
| __SetPageSwapBacked(page); |
| __SetPageUptodate(page); |
| |
| ret = -EFAULT; |
| max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); |
| if (unlikely(pgoff >= max_off)) |
| goto out_release; |
| |
| ret = shmem_add_to_page_cache(page, mapping, pgoff, NULL, |
| gfp & GFP_RECLAIM_MASK, dst_mm); |
| if (ret) |
| goto out_release; |
| |
| ret = mfill_atomic_install_pte(dst_mm, dst_pmd, dst_vma, dst_addr, |
| page, true, false); |
| if (ret) |
| goto out_delete_from_cache; |
| |
| spin_lock_irq(&info->lock); |
| info->alloced++; |
| inode->i_blocks += BLOCKS_PER_PAGE; |
| shmem_recalc_inode(inode); |
| spin_unlock_irq(&info->lock); |
| |
| SetPageDirty(page); |
| unlock_page(page); |
| return 0; |
| out_delete_from_cache: |
| delete_from_page_cache(page); |
| out_release: |
| unlock_page(page); |
| put_page(page); |
| out_unacct_blocks: |
| shmem_inode_unacct_blocks(inode, 1); |
| return ret; |
| } |
| #endif /* CONFIG_USERFAULTFD */ |
| |
| #ifdef CONFIG_TMPFS |
| static const struct inode_operations shmem_symlink_inode_operations; |
| static const struct inode_operations shmem_short_symlink_operations; |
| |
| #ifdef CONFIG_TMPFS_XATTR |
| static int shmem_initxattrs(struct inode *, const struct xattr *, void *); |
| #else |
| #define shmem_initxattrs NULL |
| #endif |
| |
| static int |
| shmem_write_begin(struct file *file, struct address_space *mapping, |
| loff_t pos, unsigned len, unsigned flags, |
| struct page **pagep, void **fsdata) |
| { |
| struct inode *inode = mapping->host; |
| struct shmem_inode_info *info = SHMEM_I(inode); |
| pgoff_t index = pos >> PAGE_SHIFT; |
| |
| /* i_rwsem is held by caller */ |
| if (unlikely(info->seals & (F_SEAL_GROW | |
| F_SEAL_WRITE | F_SEAL_FUTURE_WRITE))) { |
| if (info->seals & (F_SEAL_WRITE | F_SEAL_FUTURE_WRITE)) |
| return -EPERM; |
| if ((info->seals & F_SEAL_GROW) && pos + len > inode->i_size) |
| return -EPERM; |
| } |
| |
| return shmem_getpage(inode, index, pagep, SGP_WRITE); |
| } |
| |
| static int |
| shmem_write_end(struct file *file, struct address_space *mapping, |
| loff_t pos, unsigned len, unsigned copied, |
| struct page *page, void *fsdata) |
| { |
| struct inode *inode = mapping->host; |
| |
| if (pos + copied > inode->i_size) |
| i_size_write(inode, pos + copied); |
| |
| if (!PageUptodate(page)) { |
| struct page *head = compound_head(page); |
| if (PageTransCompound(page)) { |
| int i; |
| |
| for (i = 0; i < HPAGE_PMD_NR; i++) { |
| if (head + i == page) |
| continue; |
| clear_highpage(head + i); |
| flush_dcache_page(head + i); |
| } |
| } |
| if (copied < PAGE_SIZE) { |
| unsigned from = pos & (PAGE_SIZE - 1); |
| zero_user_segments(page, 0, from, |
| from + copied, PAGE_SIZE); |
| } |
| SetPageUptodate(head); |
| } |
| set_page_dirty(page); |
| unlock_page(page); |
| put_page(page); |
| |
| return copied; |
| } |
| |
| static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to) |
| { |
| struct file *file = iocb->ki_filp; |
| struct inode *inode = file_inode(file); |
| struct address_space *mapping = inode->i_mapping; |
| pgoff_t index; |
| unsigned long offset; |
| enum sgp_type sgp = SGP_READ; |
| int error = 0; |
| ssize_t retval = 0; |
| loff_t *ppos = &iocb->ki_pos; |
| |
| /* |
| * Might this read be for a stacking filesystem? Then when reading |
| * holes of a sparse file, we actually need to allocate those pages, |
| * and even mark them dirty, so it cannot exceed the max_blocks limit. |
| */ |
| if (!iter_is_iovec(to)) |
| sgp = SGP_CACHE; |
| |
| index = *ppos >> PAGE_SHIFT; |
| offset = *ppos & ~PAGE_MASK; |
| |
| for (;;) { |
| struct page *page = NULL; |
| pgoff_t end_index; |
| unsigned long nr, ret; |
| loff_t i_size = i_size_read(inode); |
| |
| end_index = i_size >> PAGE_SHIFT; |
| if (index > end_index) |
| break; |
| if (index == end_index) { |
| nr = i_size & ~PAGE_MASK; |
| if (nr <= offset) |
| break; |
| } |
| |
| error = shmem_getpage(inode, index, &page, sgp); |
| if (error) { |
| if (error == -EINVAL) |
| error = 0; |
| break; |
| } |
| if (page) { |
| if (sgp == SGP_CACHE) |
| set_page_dirty(page); |
| unlock_page(page); |
| } |
| |
| /* |
| * We must evaluate after, since reads (unlike writes) |
| * are called without i_rwsem protection against truncate |
| */ |
| nr = PAGE_SIZE; |
| i_size = i_size_read(inode); |
| end_index = i_size >> PAGE_SHIFT; |
| if (index == end_index) { |
| nr = i_size & ~PAGE_MASK; |
| if (nr <= offset) { |
| if (page) |
| put_page(page); |
| break; |
| } |
| } |
| nr -= offset; |
| |
| if (page) { |
| /* |
| * If users can be writing to this page using arbitrary |
| * virtual addresses, take care about potential aliasing |
| * before reading the page on the kernel side. |
| */ |
| if (mapping_writably_mapped(mapping)) |
| flush_dcache_page(page); |
| /* |
| * Mark the page accessed if we read the beginning. |
| */ |
| if (!offset) |
| mark_page_accessed(page); |
| } else { |
| page = ZERO_PAGE(0); |
| get_page(page); |
| } |
| |
| /* |
| * Ok, we have the page, and it's up-to-date, so |
| * now we can copy it to user space... |
| */ |
| ret = copy_page_to_iter(page, offset, nr, to); |
| retval += ret; |
| offset += ret; |
| index += offset >> PAGE_SHIFT; |
| offset &= ~PAGE_MASK; |
| |
| put_page(page); |
| if (!iov_iter_count(to)) |
| break; |
| if (ret < nr) { |
| error = -EFAULT; |
| break; |
| } |
| cond_resched(); |
| } |
| |
| *ppos = ((loff_t) index << PAGE_SHIFT) + offset; |
| file_accessed(file); |
| return retval ? retval : error; |
| } |
| |
| static loff_t shmem_file_llseek(struct file *file, loff_t offset, int whence) |
| { |
| struct address_space *mapping = file->f_mapping; |
| struct inode *inode = mapping->host; |
| |
| if (whence != SEEK_DATA && whence != SEEK_HOLE) |
| return generic_file_llseek_size(file, offset, whence, |
| MAX_LFS_FILESIZE, i_size_read(inode)); |
| if (offset < 0) |
| return -ENXIO; |
| |
| inode_lock(inode); |
| /* We're holding i_rwsem so we can access i_size directly */ |
| offset = mapping_seek_hole_data(mapping, offset, inode->i_size, whence); |
| if (offset >= 0) |
| offset = vfs_setpos(file, offset, MAX_LFS_FILESIZE); |
| inode_unlock(inode); |
| return offset; |
| } |
| |
| static long shmem_fallocate(struct file *file, int mode, loff_t offset, |
| loff_t len) |
| { |
| struct inode *inode = file_inode(file); |
| struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); |
| struct shmem_inode_info *info = SHMEM_I(inode); |
| struct shmem_falloc shmem_falloc; |
| pgoff_t start, index, end, undo_fallocend; |
| int error; |
| |
| if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE)) |
| return -EOPNOTSUPP; |
| |
| inode_lock(inode); |
| |
| if (mode & FALLOC_FL_PUNCH_HOLE) { |
| struct address_space *mapping = file->f_mapping; |
| loff_t unmap_start = round_up(offset, PAGE_SIZE); |
| loff_t unmap_end = round_down(offset + len, PAGE_SIZE) - 1; |
| DECLARE_WAIT_QUEUE_HEAD_ONSTACK(shmem_falloc_waitq); |
| |
| /* protected by i_rwsem */ |
| if (info->seals & (F_SEAL_WRITE | F_SEAL_FUTURE_WRITE)) { |
| error = -EPERM; |
| goto out; |
| } |
| |
| shmem_falloc.waitq = &shmem_falloc_waitq; |
| shmem_falloc.start = (u64)unmap_start >> PAGE_SHIFT; |
| shmem_falloc.next = (unmap_end + 1) >> PAGE_SHIFT; |
| spin_lock(&inode->i_lock); |
| inode->i_private = &shmem_falloc; |
| spin_unlock(&inode->i_lock); |
| |
| if ((u64)unmap_end > (u64)unmap_start) |
| unmap_mapping_range(mapping, unmap_start, |
| 1 + unmap_end - unmap_start, 0); |
| shmem_truncate_range(inode, offset, offset + len - 1); |
| /* No need to unmap again: hole-punching leaves COWed pages */ |
| |
| spin_lock(&inode->i_lock); |
| inode->i_private = NULL; |
| wake_up_all(&shmem_falloc_waitq); |
| WARN_ON_ONCE(!list_empty(&shmem_falloc_waitq.head)); |
| spin_unlock(&inode->i_lock); |
| error = 0; |
| goto out; |
| } |
| |
| /* We need to check rlimit even when FALLOC_FL_KEEP_SIZE */ |
| error = inode_newsize_ok(inode, offset + len); |
| if (error) |
| goto out; |
| |
| if ((info->seals & F_SEAL_GROW) && offset + len > inode->i_size) { |
| error = -EPERM; |
| goto out; |
| } |
| |
| start = offset >> PAGE_SHIFT; |
| end = (offset + len + PAGE_SIZE - 1) >> PAGE_SHIFT; |
| /* Try to avoid a swapstorm if len is impossible to satisfy */ |
| if (sbinfo->max_blocks && end - start > sbinfo->max_blocks) { |
| error = -ENOSPC; |
| goto out; |
| } |
| |
| shmem_falloc.waitq = NULL; |
| shmem_falloc.start = start; |
| shmem_falloc.next = start; |
| shmem_falloc.nr_falloced = 0; |
| shmem_falloc.nr_unswapped = 0; |
| spin_lock(&inode->i_lock); |
| inode->i_private = &shmem_falloc; |
| spin_unlock(&inode->i_lock); |
| |
| /* |
| * info->fallocend is only relevant when huge pages might be |
| * involved: to prevent split_huge_page() freeing fallocated |
| * pages when FALLOC_FL_KEEP_SIZE committed beyond i_size. |
| */ |
| undo_fallocend = info->fallocend; |
| if (info->fallocend < end) |
| info->fallocend = end; |
| |
| for (index = start; index < end; ) { |
| struct page *page; |
| |
| /* |
| * Good, the fallocate(2) manpage permits EINTR: we may have |
| * been interrupted because we are using up too much memory. |
| */ |
| if (signal_pending(current)) |
| error = -EINTR; |
| else if (shmem_falloc.nr_unswapped > shmem_falloc.nr_falloced) |
| error = -ENOMEM; |
| else |
| error = shmem_getpage(inode, index, &page, SGP_FALLOC); |
| if (error) { |
| info->fallocend = undo_fallocend; |
| /* Remove the !PageUptodate pages we added */ |
| if (index > start) { |
| shmem_undo_range(inode, |
| (loff_t)start << PAGE_SHIFT, |
| ((loff_t)index << PAGE_SHIFT) - 1, true); |
| } |
| goto undone; |
| } |
| |
| index++; |
| /* |
| * Here is a more important optimization than it appears: |
| * a second SGP_FALLOC on the same huge page will clear it, |
| * making it PageUptodate and un-undoable if we fail later. |
| */ |
| if (PageTransCompound(page)) { |
| index = round_up(index, HPAGE_PMD_NR); |
| /* Beware 32-bit wraparound */ |
| if (!index) |
| index--; |
| } |
| |
| /* |
| * Inform shmem_writepage() how far we have reached. |
| * No need for lock or barrier: we have the page lock. |
| */ |
| if (!PageUptodate(page)) |
| shmem_falloc.nr_falloced += index - shmem_falloc.next; |
| shmem_falloc.next = index; |
| |
| /* |
| * If !PageUptodate, leave it that way so that freeable pages |
| * can be recognized if we need to rollback on error later. |
| * But set_page_dirty so that memory pressure will swap rather |
| * than free the pages we are allocating (and SGP_CACHE pages |
| * might still be clean: we now need to mark those dirty too). |
| */ |
| set_page_dirty(page); |
| unlock_page(page); |
| put_page(page); |
| cond_resched(); |
| } |
| |
| if (!(mode & FALLOC_FL_KEEP_SIZE) && offset + len > inode->i_size) |
| i_size_write(inode, offset + len); |
| inode->i_ctime = current_time(inode); |
| undone: |
| spin_lock(&inode->i_lock); |
| inode->i_private = NULL; |
| spin_unlock(&inode->i_lock); |
| out: |
| inode_unlock(inode); |
| return error; |
| } |
| |
| static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf) |
| { |
| struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb); |
| |
| buf->f_type = TMPFS_MAGIC; |
| buf->f_bsize = PAGE_SIZE; |
| buf->f_namelen = NAME_MAX; |
| if (sbinfo->max_blocks) { |
| buf->f_blocks = sbinfo->max_blocks; |
| buf->f_bavail = |
| buf->f_bfree = sbinfo->max_blocks - |
| percpu_counter_sum(&sbinfo->used_blocks); |
| } |
| if (sbinfo->max_inodes) { |
| buf->f_files = sbinfo->max_inodes; |
| buf->f_ffree = sbinfo->free_inodes; |
| } |
| /* else leave those fields 0 like simple_statfs */ |
| |
| buf->f_fsid = uuid_to_fsid(dentry->d_sb->s_uuid.b); |
| |
| return 0; |
| } |
| |
| /* |
| * File creation. Allocate an inode, and we're done.. |
| */ |
| static int |
| shmem_mknod(struct user_namespace *mnt_userns, struct inode *dir, |
| struct dentry *dentry, umode_t mode, dev_t dev) |
| { |
| struct inode *inode; |
| int error = -ENOSPC; |
| |
| inode = shmem_get_inode(dir->i_sb, dir, mode, dev, VM_NORESERVE); |
| if (inode) { |
| error = simple_acl_create(dir, inode); |
| if (error) |
| goto out_iput; |
| error = security_inode_init_security(inode, dir, |
| &dentry->d_name, |
| shmem_initxattrs, NULL); |
| if (error && error != -EOPNOTSUPP) |
| goto out_iput; |
| |
| error = 0; |
| dir->i_size += BOGO_DIRENT_SIZE; |
| dir->i_ctime = dir->i_mtime = current_time(dir); |
| d_instantiate(dentry, inode); |
| dget(dentry); /* Extra count - pin the dentry in core */ |
| } |
| return error; |
| out_iput: |
| iput(inode); |
| return error; |
| } |
| |
| static int |
| shmem_tmpfile(struct user_namespace *mnt_userns, struct inode *dir, |
| struct dentry *dentry, umode_t mode) |
| { |
| struct inode *inode; |
| int error = -ENOSPC; |
| |
| inode = shmem_get_inode(dir->i_sb, dir, mode, 0, VM_NORESERVE); |
| if (inode) { |
| error = security_inode_init_security(inode, dir, |
| NULL, |
| shmem_initxattrs, NULL); |
| if (error && error != -EOPNOTSUPP) |
| goto out_iput; |
| error = simple_acl_create(dir, inode); |
| if (error) |
| goto out_iput; |
| d_tmpfile(dentry, inode); |
| } |
| return error; |
| out_iput: |
| iput(inode); |
| return error; |
| } |
| |
| static int shmem_mkdir(struct user_namespace *mnt_userns, struct inode *dir, |
| struct dentry *dentry, umode_t mode) |
| { |
| int error; |
| |
| if ((error = shmem_mknod(&init_user_ns, dir, dentry, |
| mode | S_IFDIR, 0))) |
| return error; |
| inc_nlink(dir); |
| return 0; |
| } |
| |
| static int shmem_create(struct user_namespace *mnt_userns, struct inode *dir, |
| struct dentry *dentry, umode_t mode, bool excl) |
| { |
| return shmem_mknod(&init_user_ns, dir, dentry, mode | S_IFREG, 0); |
| } |
| |
| /* |
| * Link a file.. |
| */ |
| static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) |
| { |
| struct inode *inode = d_inode(old_dentry); |
| int ret = 0; |
| |
| /* |
| * No ordinary (disk based) filesystem counts links as inodes; |
| * but each new link needs a new dentry, pinning lowmem, and |
| * tmpfs dentries cannot be pruned until they are unlinked. |
| * But if an O_TMPFILE file is linked into the tmpfs, the |
| * first link must skip that, to get the accounting right. |
| */ |
| if (inode->i_nlink) { |
| ret = shmem_reserve_inode(inode->i_sb, NULL); |
| if (ret) |
| goto out; |
| } |
| |
| dir->i_size += BOGO_DIRENT_SIZE; |
| inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode); |
| inc_nlink(inode); |
| ihold(inode); /* New dentry reference */ |
| dget(dentry); /* Extra pinning count for the created dentry */ |
| d_instantiate(dentry, inode); |
| out: |
| return ret; |
| } |
| |
| static int shmem_unlink(struct inode *dir, struct dentry *dentry) |
| { |
| struct inode *inode = d_inode(dentry); |
| |
| if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) |
| shmem_free_inode(inode->i_sb); |
| |
| dir->i_size -= BOGO_DIRENT_SIZE; |
| inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode); |
| drop_nlink(inode); |
| dput(dentry); /* Undo the count from "create" - this does all the work */ |
| return 0; |
| } |
| |
| static int shmem_rmdir(struct inode *dir, struct dentry *dentry) |
| { |
| if (!simple_empty(dentry)) |
| return -ENOTEMPTY; |
| |
| drop_nlink(d_inode(dentry)); |
| drop_nlink(dir); |
| return shmem_unlink(dir, dentry); |
| } |
| |
| static int shmem_exchange(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry) |
| { |
| bool old_is_dir = d_is_dir(old_dentry); |
| bool new_is_dir = d_is_dir(new_dentry); |
| |
| if (old_dir != new_dir && old_is_dir != new_is_dir) { |
| if (old_is_dir) { |
| drop_nlink(old_dir); |
| inc_nlink(new_dir); |
| } else { |
| drop_nlink(new_dir); |
| inc_nlink(old_dir); |
| } |
| } |
| old_dir->i_ctime = old_dir->i_mtime = |
| new_dir->i_ctime = new_dir->i_mtime = |
| d_inode(old_dentry)->i_ctime = |
| d_inode(new_dentry)->i_ctime = current_time(old_dir); |
| |
| return 0; |
| } |
| |
| static int shmem_whiteout(struct user_namespace *mnt_userns, |
| struct inode *old_dir, struct dentry *old_dentry) |
| { |
| struct dentry *whiteout; |
| int error; |
| |
| whiteout = d_alloc(old_dentry->d_parent, &old_dentry->d_name); |
| if (!whiteout) |
| return -ENOMEM; |
| |
| error = shmem_mknod(&init_user_ns, old_dir, whiteout, |
| S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV); |
| dput(whiteout); |
| if (error) |
| return error; |
| |
| /* |
| * Cheat and hash the whiteout while the old dentry is still in |
| * place, instead of playing games with FS_RENAME_DOES_D_MOVE. |
| * |
| * d_lookup() will consistently find one of them at this point, |
| * not sure which one, but that isn't even important. |
| */ |
| d_rehash(whiteout); |
| return 0; |
| } |
| |
| /* |
| * The VFS layer already does all the dentry stuff for rename, |
| * we just have to decrement the usage count for the target if |
| * it exists so that the VFS layer correctly free's it when it |
| * gets overwritten. |
| */ |
| static int shmem_rename2(struct user_namespace *mnt_userns, |
| struct inode *old_dir, struct dentry *old_dentry, |
| struct inode *new_dir, struct dentry *new_dentry, |
| unsigned int flags) |
| { |
| struct inode *inode = d_inode(old_dentry); |
| int they_are_dirs = S_ISDIR(inode->i_mode); |
| |
| if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT)) |
| return -EINVAL; |
| |
| if (flags & RENAME_EXCHANGE) |
| return shmem_exchange(old_dir, old_dentry, new_dir, new_dentry); |
| |
| if (!simple_empty(new_dentry)) |
| return -ENOTEMPTY; |
| |
| if (flags & RENAME_WHITEOUT) { |
| int error; |
| |
| error = shmem_whiteout(&init_user_ns, old_dir, old_dentry); |
| if (error) |
| return error; |
| } |
| |
| if (d_really_is_positive(new_dentry)) { |
| (void) shmem_unlink(new_dir, new_dentry); |
| if (they_are_dirs) { |
| drop_nlink(d_inode(new_dentry)); |
| drop_nlink(old_dir); |
| } |
| } else if (they_are_dirs) { |
| drop_nlink(old_dir); |
| inc_nlink(new_dir); |
| } |
| |
| old_dir->i_size -= BOGO_DIRENT_SIZE; |
| new_dir->i_size += BOGO_DIRENT_SIZE; |
| old_dir->i_ctime = old_dir->i_mtime = |
| new_dir->i_ctime = new_dir->i_mtime = |
| inode->i_ctime = current_time(old_dir); |
| return 0; |
| } |
| |
| static int shmem_symlink(struct user_namespace *mnt_userns, struct inode *dir, |
| struct dentry *dentry, const char *symname) |
| { |
| int error; |
| int len; |
| struct inode *inode; |
| struct page *page; |
| |
| len = strlen(symname) + 1; |
| if (len > PAGE_SIZE) |
| return -ENAMETOOLONG; |
| |
| inode = shmem_get_inode(dir->i_sb, dir, S_IFLNK | 0777, 0, |
| VM_NORESERVE); |
| if (!inode) |
| return -ENOSPC; |
| |
| error = security_inode_init_security(inode, dir, &dentry->d_name, |
| shmem_initxattrs, NULL); |
| if (error && error != -EOPNOTSUPP) { |
| iput(inode); |
| return error; |
| } |
| |
| inode->i_size = len-1; |
| if (len <= SHORT_SYMLINK_LEN) { |
| inode->i_link = kmemdup(symname, len, GFP_KERNEL); |
| if (!inode->i_link) { |
| iput(inode); |
| return -ENOMEM; |
| } |
| inode->i_op = &shmem_short_symlink_operations; |
| } else { |
| inode_nohighmem(inode); |
| error = shmem_getpage(inode, 0, &page, SGP_WRITE); |
| if (error) { |
| iput(inode); |
| return error; |
| } |
| inode->i_mapping->a_ops = &shmem_aops; |
| inode->i_op = &shmem_symlink_inode_operations; |
| memcpy(page_address(page), symname, len); |
| SetPageUptodate(page); |
| set_page_dirty(page); |
| unlock_page(page); |
| put_page(page); |
| } |
| dir->i_size += BOGO_DIRENT_SIZE; |
| dir->i_ctime = dir->i_mtime = current_time(dir); |
| d_instantiate(dentry, inode); |
| dget(dentry); |
| return 0; |
| } |
| |
| static void shmem_put_link(void *arg) |
| { |
| mark_page_accessed(arg); |
| put_page(arg); |
| } |
| |
| static const char *shmem_get_link(struct dentry *dentry, |
| struct inode *inode, |
| struct delayed_call *done) |
| { |
| struct page *page = NULL; |
| int error; |
| if (!dentry) { |
| page = find_get_page(inode->i_mapping, 0); |
| if (!page) |
| return ERR_PTR(-ECHILD); |
| if (!PageUptodate( |