From 991c2c5980fb97ae6194f7c46b44f9446629eb4e Mon Sep 17 00:00:00 2001 From: Dave Chinner Date: Wed, 26 May 2021 19:57:42 -0700 Subject: [PATCH] xfs: btree format inode forks can have zero extents xfs/538 is assert failing with this trace when testing with directory block sizes of 64kB: XFS: Assertion failed: !xfs_need_iread_extents(ifp), file: fs/xfs/libxfs/xfs_bmap.c, line: 608 .... Call Trace: xfs_bmap_btree_to_extents+0x2a9/0x470 ? kmem_cache_alloc+0xe7/0x220 __xfs_bunmapi+0x4ca/0xdf0 xfs_bunmapi+0x1a/0x30 xfs_dir2_shrink_inode+0x71/0x210 xfs_dir2_block_to_sf+0x2ae/0x410 xfs_dir2_block_removename+0x21a/0x280 xfs_dir_removename+0x195/0x1d0 xfs_remove+0x244/0x460 xfs_vn_unlink+0x53/0xa0 ? selinux_inode_unlink+0x13/0x20 vfs_unlink+0x117/0x220 do_unlinkat+0x1a2/0x2d0 __x64_sys_unlink+0x42/0x60 do_syscall_64+0x3a/0x70 entry_SYSCALL_64_after_hwframe+0x44/0xae This is a check to ensure that the extents have been read into memory before we are doing a ifork btree manipulation. This assert is bogus in the above case. We have a fragmented directory block that has more extents in it than can fit in extent format, so the inode data fork is in btree format. xfs_dir2_shrink_inode() asks to remove all remaining 16 filesystem blocks from the inode so it can convert to short form, and __xfs_bunmapi() removes all the extents. We now have a data fork in btree format but have zero extents in the fork. This incorrectly trips the xfs_need_iread_extents() assert because it assumes that an empty extent btree means the extent tree has not been read into memory yet. This is clearly not the case with xfs_bunmapi(), as it has an explicit call to xfs_iread_extents() in it to pull the extents into memory before it starts unmapping. Also, the assert directly after this bogus one is: ASSERT(ifp->if_format == XFS_DINODE_FMT_BTREE); Which covers the context in which it is legal to call xfs_bmap_btree_to_extents just fine. Hence we should just remove the bogus assert as it is clearly wrong and causes a regression. The returns the test behaviour to the pre-existing assert failure in xfs_dir2_shrink_inode() that indicates xfs_bunmapi() has failed to remove all the extents in the range it was asked to unmap. Signed-off-by: Dave Chinner Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong --- fs/xfs/libxfs/xfs_bmap.c | 1 - 1 file changed, 1 deletion(-) diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c index 7e3b9b0..3f8b6da0 100644 --- a/fs/xfs/libxfs/xfs_bmap.c +++ b/fs/xfs/libxfs/xfs_bmap.c @@ -605,7 +605,6 @@ xfs_bmap_btree_to_extents( ASSERT(cur); ASSERT(whichfork != XFS_COW_FORK); - ASSERT(!xfs_need_iread_extents(ifp)); ASSERT(ifp->if_format == XFS_DINODE_FMT_BTREE); ASSERT(be16_to_cpu(rblock->bb_level) == 1); ASSERT(be16_to_cpu(rblock->bb_numrecs) == 1); -- 2.7.4