From: "Darrick J. Wong" <djwong@kernel.org> mainline inclusion from mainline-v6.3-rc4 commit fcde88af6a783d32e735dd2615528e2bf7a0f533 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I9PFXW Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- In xfs_buffered_write_iomap_begin, @icur is the iext cursor for the data fork and @ccur is the cursor for the cow fork. Pass in whichever cursor corresponds to allocfork, because otherwise the xfs_iext_prev_extent call can use the data fork cursor to walk off the end of the cow fork structure. Best case it returns the wrong results, worst case it does this: stack segment: 0000 [#1] PREEMPT SMP CPU: 2 PID: 3141909 Comm: fsstress Tainted: G W 6.3.0-rc2-xfsx #6.3.0-rc2 7bf5cc2e98997627cae5c930d890aba3aeec65dd Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20171121_152543-x86-ol7-builder-01.us.oracle.com-4.el7.1 04/01/2014 RIP: 0010:xfs_iext_prev+0x71/0x150 [xfs] RSP: 0018:ffffc90002233aa8 EFLAGS: 00010297 RAX: 000000000000000f RBX: 000000000000000e RCX: 000000000000000c RDX: 0000000000000002 RSI: 000000000000000e RDI: ffff8883d0019ba0 RBP: 989642409af8a7a7 R08: ffffea0000000001 R09: 0000000000000002 R10: 0000000000000000 R11: 000000000000000c R12: ffffc90002233b00 R13: ffff8883d0019ba0 R14: 989642409af8a6bf R15: 000ffffffffe0000 FS: 00007fdf8115f740(0000) GS:ffff88843fd00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fdf8115e000 CR3: 0000000357256000 CR4: 00000000003506e0 Call Trace: <TASK> xfs_iomap_prealloc_size.constprop.0.isra.0+0x1a6/0x410 [xfs 619a268fb2406d68bd34e007a816b27e70abc22c] xfs_buffered_write_iomap_begin+0xa87/0xc60 [xfs 619a268fb2406d68bd34e007a816b27e70abc22c] iomap_iter+0x132/0x2f0 iomap_file_buffered_write+0x92/0x330 xfs_file_buffered_write+0xb1/0x330 [xfs 619a268fb2406d68bd34e007a816b27e70abc22c] vfs_write+0x2eb/0x410 ksys_write+0x65/0xe0 do_syscall_64+0x2b/0x80 entry_SYSCALL_64_after_hwframe+0x46/0xb0 Found by xfs/538 in alwayscow mode, but this doesn't seem particular to that test. Fixes: 590b16516ef3 ("xfs: refactor xfs_iomap_prealloc_size") Actually-Fixes: 66ae56a53f0e ("xfs: introduce an always_cow mode") Signed-off-by: Darrick J. Wong <djwong@kernel.org> Signed-off-by: Zizhi Wo <wozizhi@huawei.com> --- fs/xfs/xfs_iomap.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c index ae96ac52c974..8fa09970b0d4 100644 --- a/fs/xfs/xfs_iomap.c +++ b/fs/xfs/xfs_iomap.c @@ -1027,9 +1027,12 @@ xfs_buffered_write_iomap_begin( */ if (xfs_has_allocsize(mp)) prealloc_blocks = mp->m_allocsize_blocks; - else + else if (allocfork == XFS_DATA_FORK) prealloc_blocks = xfs_iomap_prealloc_size(ip, allocfork, offset, count, &icur); + else + prealloc_blocks = xfs_iomap_prealloc_size(ip, allocfork, + offset, count, &ccur); if (prealloc_blocks) { xfs_extlen_t align; xfs_off_t end_offset; -- 2.39.2