linux.git/fs/ext4/migrate.c, branch v6.3

ext4: fix warning in 'ext4_da_release_space'

2022-11-06T05:07:59+00:00

Syzkaller report issue as follows:
EXT4-fs (loop0): Free/Dirty block details
EXT4-fs (loop0): free_blocks=0
EXT4-fs (loop0): dirty_blocks=0
EXT4-fs (loop0): Block reservation details
EXT4-fs (loop0): i_reserved_data_blocks=0
EXT4-fs warning (device loop0): ext4_da_release_space:1527: ext4_da_release_space: ino 18, to_free 1 with only 0 reserved data blocks
------------[ cut here ]------------
WARNING: CPU: 0 PID: 92 at fs/ext4/inode.c:1528 ext4_da_release_space+0x25e/0x370 fs/ext4/inode.c:1524
Modules linked in:
CPU: 0 PID: 92 Comm: kworker/u4:4 Not tainted 6.0.0-syzkaller-09423-g493ffd6605b2 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/22/2022
Workqueue: writeback wb_workfn (flush-7:0)
RIP: 0010:ext4_da_release_space+0x25e/0x370 fs/ext4/inode.c:1528
RSP: 0018:ffffc900015f6c90 EFLAGS: 00010296
RAX: 42215896cd52ea00 RBX: 0000000000000000 RCX: 42215896cd52ea00
RDX: 0000000000000000 RSI: 0000000080000001 RDI: 0000000000000000
RBP: 1ffff1100e907d96 R08: ffffffff816aa79d R09: fffff520002bece5
R10: fffff520002bece5 R11: 1ffff920002bece4 R12: ffff888021fd2000
R13: ffff88807483ecb0 R14: 0000000000000001 R15: ffff88807483e740
FS:  0000000000000000(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005555569ba628 CR3: 000000000c88e000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 
 ext4_es_remove_extent+0x1ab/0x260 fs/ext4/extents_status.c:1461
 mpage_release_unused_pages+0x24d/0xef0 fs/ext4/inode.c:1589
 ext4_writepages+0x12eb/0x3be0 fs/ext4/inode.c:2852
 do_writepages+0x3c3/0x680 mm/page-writeback.c:2469
 __writeback_single_inode+0xd1/0x670 fs/fs-writeback.c:1587
 writeback_sb_inodes+0xb3b/0x18f0 fs/fs-writeback.c:1870
 wb_writeback+0x41f/0x7b0 fs/fs-writeback.c:2044
 wb_do_writeback fs/fs-writeback.c:2187 [inline]
 wb_workfn+0x3cb/0xef0 fs/fs-writeback.c:2227
 process_one_work+0x877/0xdb0 kernel/workqueue.c:2289
 worker_thread+0xb14/0x1330 kernel/workqueue.c:2436
 kthread+0x266/0x300 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
 

Above issue may happens as follows:
ext4_da_write_begin
  ext4_create_inline_data
    ext4_clear_inode_flag(inode, EXT4_INODE_EXTENTS);
    ext4_set_inode_flag(inode, EXT4_INODE_INLINE_DATA);
__ext4_ioctl
  ext4_ext_migrate -> will lead to eh->eh_entries not zero, and set extent flag
ext4_da_write_begin
  ext4_da_convert_inline_data_to_extent
    ext4_da_write_inline_data_begin
      ext4_da_map_blocks
        ext4_insert_delayed_block
	  if (!ext4_es_scan_clu(inode, &ext4_es_is_delonly, lblk))
	    if (!ext4_es_scan_clu(inode, &ext4_es_is_mapped, lblk))
	      ext4_clu_mapped(inode, EXT4_B2C(sbi, lblk)); -> will return 1
	       allocated = true;
          ext4_es_insert_delayed_block(inode, lblk, allocated);
ext4_writepages
  mpage_map_and_submit_extent(handle, &mpd, &give_up_on_write); -> return -ENOSPC
  mpage_release_unused_pages(&mpd, give_up_on_write); -> give_up_on_write == 1
    ext4_es_remove_extent
      ext4_da_release_space(inode, reserved);
        if (unlikely(to_free > ei->i_reserved_data_blocks))
	  -> to_free == 1  but ei->i_reserved_data_blocks == 0
	  -> then trigger warning as above

To solve above issue, forbid inode do migrate which has inline data.

Cc: stable@kernel.org
Reported-by: syzbot+c740bb18df70ad00952e@syzkaller.appspotmail.com
Signed-off-by: Ye Bin 
Reviewed-by: Jan Kara 
Link: https://lore.kernel.org/r/20221018022701.683489-1-yebin10@huawei.com
Signed-off-by: Theodore Ts'o

ext4: factor out ext4_free_ext_path()

2022-10-01T03:46:54+00:00

Factor out ext4_free_ext_path() to free extent path. As after previous patch
'ext4_ext_drop_refs()' is only used in 'extents.c', so make it static.

Signed-off-by: Ye Bin 
Reviewed-by: Jan Kara 
Link: https://lore.kernel.org/r/20220924021211.3831551-3-yebin10@huawei.com
Signed-off-by: Theodore Ts'o

ext4: recover csum seed of tmp_inode after migrating to extents

2022-08-03T03:56:02+00:00

When migrating to extents, the checksum seed of temporary inode
need to be replaced by inode's, otherwise the inode checksums
will be incorrect when swapping the inodes data.

However, the temporary inode can not match it's checksum to
itself since it has lost it's own checksum seed.

mkfs.ext4 -F /dev/sdc
mount /dev/sdc /mnt/sdc
xfs_io -fc "pwrite 4k 4k" -c "fsync" /mnt/sdc/testfile
chattr -e /mnt/sdc/testfile
chattr +e /mnt/sdc/testfile
umount /dev/sdc
fsck -fn /dev/sdc

========
...
Pass 1: Checking inodes, blocks, and sizes
Inode 13 passes checks, but checksum does not match inode.  Fix? no
...
========

The fix is simple, save the checksum seed of temporary inode, and
recover it after migrating to extents.

Fixes: e81c9302a6c3 ("ext4: set csum seed in tmp inode while migrating to extents")
Signed-off-by: Li Lingfeng 
Reviewed-by: Jan Kara 
Link: https://lore.kernel.org/r/20220617062515.2113438-1-lilingfeng3@huawei.com
Signed-off-by: Theodore Ts'o

ext4: fix a doubled word "need" in a comment

2022-06-18T23:36:20+00:00

Signed-off-by: Xiang wangx 
Link: https://lore.kernel.org/r/20220605091503.12513-1-wangxiang@cdjrlc.com
Signed-off-by: Theodore Ts'o

fs/ext4: fix comments mentioning i_mutex

2022-02-03T15:57:53+00:00

inode->i_mutex has been replaced with inode->i_rwsem long ago. Fix
comments still mentioning i_mutex.

Signed-off-by: hongnanli 
Link: https://lore.kernel.org/r/20220121070611.21618-1-hongnan.li@linux.alibaba.com
Signed-off-by: Theodore Ts'o

ext4: don't use the orphan list when migrating an inode

2022-01-10T18:25:56+00:00

We probably want to remove the indirect block to extents migration
feature after a deprecation window, but until then, let's fix a
potential data loss problem caused by the fact that we put the
tmp_inode on the orphan list.  In the unlikely case where we crash and
do a journal recovery, the data blocks belonging to the inode being
migrated are also represented in the tmp_inode on the orphan list ---
and so its data blocks will get marked unallocated, and available for
reuse.

Instead, stop putting the tmp_inode on the oprhan list.  So in the
case where we crash while migrating the inode, we'll leak an inode,
which is not a disaster.  It will be easily fixed the next time we run
fsck, and it's better than potentially having blocks getting claimed
by two different files, and losing data as a result.

Signed-off-by: Theodore Ts'o 
Reviewed-by: Lukas Czerner 
Cc: stable@kernel.org

ext4: set csum seed in tmp inode while migrating to extents

2022-01-10T18:25:56+00:00

When migrating to extents, the temporary inode will have it's own checksum
seed.  This means that, when swapping the inodes data, the inode checksums
will be incorrect.

This can be fixed by recalculating the extents checksums again.  Or simply
by copying the seed into the temporary inode.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=213357
Reported-by: Jeroen van Wolffelaar 
Signed-off-by: Luís Henriques 
Link: https://lore.kernel.org/r/20211214175058.19511-1-lhenriques@suse.de
Signed-off-by: Theodore Ts'o 
Cc: stable@kernel.org

ext4: fix various seppling typos

2021-04-10T03:14:59+00:00

Signed-off-by: Bhaskar Chowdhury 
Link: https://lore.kernel.org/r/cover.1616840203.git.unixbhaskar@gmail.com
Signed-off-by: Theodore Ts'o

ext4: handle ext4_mark_inode_dirty errors

2020-06-04T03:16:50+00:00

ext4_mark_inode_dirty() can fail for real reasons. Ignoring its return
value may lead ext4 to ignore real failures that would result in
corruption / crashes. Harden ext4_mark_inode_dirty error paths to fail
as soon as possible and return errors to the caller whenever
appropriate.

One of the possible scnearios when this bug could affected is that
while creating a new inode, its directory entry gets added
successfully but while writing the inode itself mark_inode_dirty
returns error which is ignored. This would result in inconsistency
that the directory entry points to a non-existent inode.

Ran gce-xfstests smoke tests and verified that there were no
regressions.

Signed-off-by: Harshad Shirwadkar 
Link: https://lore.kernel.org/r/20200427013438.219117-1-harshadshirwadkar@gmail.com
Signed-off-by: Theodore Ts'o

ext4: fix race between writepages and enabling EXT4_EXTENTS_FL

2020-02-22T00:32:07+00:00

If EXT4_EXTENTS_FL is set on an inode while ext4_writepages() is running
on it, the following warning in ext4_add_complete_io() can be hit:

WARNING: CPU: 1 PID: 0 at fs/ext4/page-io.c:234 ext4_put_io_end_defer+0xf0/0x120

Here's a minimal reproducer (not 100% reliable) (root isn't required):

        while true; do
                sync
        done &
        while true; do
                rm -f file
                touch file
                chattr -e file
                echo X >> file
                chattr +e file
        done

The problem is that in ext4_writepages(), ext4_should_dioread_nolock()
(which only returns true on extent-based files) is checked once to set
the number of reserved journal credits, and also again later to select
the flags for ext4_map_blocks() and copy the reserved journal handle to
ext4_io_end::handle.  But if EXT4_EXTENTS_FL is being concurrently set,
the first check can see dioread_nolock disabled while the later one can
see it enabled, causing the reserved handle to unexpectedly be NULL.

Since changing EXT4_EXTENTS_FL is uncommon, and there may be other races
related to doing so as well, fix this by synchronizing changing
EXT4_EXTENTS_FL with ext4_writepages() via the existing
s_writepages_rwsem (previously called s_journal_flag_rwsem).

This was originally reported by syzbot without a reproducer at
https://syzkaller.appspot.com/bug?extid=2202a584a00fffd19fbf,
but now that dioread_nolock is the default I also started seeing this
when running syzkaller locally.

Link: https://lore.kernel.org/r/20200219183047.47417-3-ebiggers@kernel.org
Reported-by: syzbot+2202a584a00fffd19fbf@syzkaller.appspotmail.com
Fixes: 6b523df4fb5a ("ext4: use transaction reservation for extent conversion in ext4_end_io")
Signed-off-by: Eric Biggers 
Signed-off-by: Theodore Ts'o 
Reviewed-by: Jan Kara 
Cc: stable@kernel.org