New code for 5.4:
- Remove KM_SLEEP/KM_NOSLEEP.
- Ensure that memory buffers for IO are properly sector-aligned to avoid
problems that the block layer doesn't check.
- Make the bmap scrubber more efficient in its record checking.
- Don't crash xfs_db when superblock inode geometry is corrupt.
- Fix btree key helper functions.
- Remove unneeded error returns for things that can't fail.
- Fix buffer logging bugs in repair.
- Clean up iterator return values.
- Speed up directory entry creation.
- Enable allocation of xattr value memory buffer during lookup.
- Fix readahead racing with truncate/punch hole.
- Other minor cleanups.
- Fix one AGI/AGF deadlock with RENAME_WHITEOUT.
xfs: Fix deadlock between AGI and AGF with RENAME_WHITEOUT
When performing rename operation with RENAME_WHITEOUT flag, we will
hold AGF lock to allocate or free extents in manipulating the dirents
firstly, and then doing the xfs_iunlink_remove() call last to hold
AGI lock to modify the tmpfile info, so we the lock order AGI->AGF.
The big problem here is that we have an ordering constraint on AGF
and AGI locking - inode allocation locks the AGI, then can allocate
a new extent for new inodes, locking the AGF after the AGI. Hence
the ordering that is imposed by other parts of the code is AGI before
AGF. So we get an ABBA deadlock between the AGI and AGF here.
Process A:
Call trace:
? __schedule+0x2bd/0x620
schedule+0x33/0x90
schedule_timeout+0x17d/0x290
__down_common+0xef/0x125
? xfs_buf_find+0x215/0x6c0 [xfs]
down+0x3b/0x50
xfs_buf_lock+0x34/0xf0 [xfs]
xfs_buf_find+0x215/0x6c0 [xfs]
xfs_buf_get_map+0x37/0x230 [xfs]
xfs_buf_read_map+0x29/0x190 [xfs]
xfs_trans_read_buf_map+0x13d/0x520 [xfs]
xfs_read_agf+0xa6/0x180 [xfs]
? schedule_timeout+0x17d/0x290
xfs_alloc_read_agf+0x52/0x1f0 [xfs]
xfs_alloc_fix_freelist+0x432/0x590 [xfs]
? down+0x3b/0x50
? xfs_buf_lock+0x34/0xf0 [xfs]
? xfs_buf_find+0x215/0x6c0 [xfs]
xfs_alloc_vextent+0x301/0x6c0 [xfs]
xfs_ialloc_ag_alloc+0x182/0x700 [xfs]
? _xfs_trans_bjoin+0x72/0xf0 [xfs]
xfs_dialloc+0x116/0x290 [xfs]
xfs_ialloc+0x6d/0x5e0 [xfs]
? xfs_log_reserve+0x165/0x280 [xfs]
xfs_dir_ialloc+0x8c/0x240 [xfs]
xfs_create+0x35a/0x610 [xfs]
xfs_generic_create+0x1f1/0x2f0 [xfs]
...
Process B:
Call trace:
? __schedule+0x2bd/0x620
? xfs_bmapi_allocate+0x245/0x380 [xfs]
schedule+0x33/0x90
schedule_timeout+0x17d/0x290
? xfs_buf_find+0x1fd/0x6c0 [xfs]
__down_common+0xef/0x125
? xfs_buf_get_map+0x37/0x230 [xfs]
? xfs_buf_find+0x215/0x6c0 [xfs]
down+0x3b/0x50
xfs_buf_lock+0x34/0xf0 [xfs]
xfs_buf_find+0x215/0x6c0 [xfs]
xfs_buf_get_map+0x37/0x230 [xfs]
xfs_buf_read_map+0x29/0x190 [xfs]
xfs_trans_read_buf_map+0x13d/0x520 [xfs]
xfs_read_agi+0xa8/0x160 [xfs]
xfs_iunlink_remove+0x6f/0x2a0 [xfs]
? current_time+0x46/0x80
? xfs_trans_ichgtime+0x39/0xb0 [xfs]
xfs_rename+0x57a/0xae0 [xfs]
xfs_vn_rename+0xe4/0x150 [xfs]
...
In this patch we move the xfs_iunlink_remove() call to
before acquiring the AGF lock to preserve correct AGI/AGF locking
order.
Signed-off-by: kaixuxia <kaixuxia@tencent.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
1 file changed
