diff options
| author | Baokun Li <libaokun1@huawei.com> | 2022-05-28 19:00:15 +0800 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2022-06-18 19:35:43 -0400 |
| commit | a08f789d2ab5242c07e716baf9a835725046be89 (patch) | |
| tree | 32eb247cd792bed4a5ff31fc1eef2174755afc40 | |
| parent | 85456054e10b0247920b00422d27365e689d9f4a (diff) | |
ext4: fix bug_on ext4_mb_use_inode_pa
Hulk Robot reported a BUG_ON:
==================================================================
kernel BUG at fs/ext4/mballoc.c:3211!
[...]
RIP: 0010:ext4_mb_mark_diskspace_used.cold+0x85/0x136f
[...]
Call Trace:
ext4_mb_new_blocks+0x9df/0x5d30
ext4_ext_map_blocks+0x1803/0x4d80
ext4_map_blocks+0x3a4/0x1a10
ext4_writepages+0x126d/0x2c30
do_writepages+0x7f/0x1b0
__filemap_fdatawrite_range+0x285/0x3b0
file_write_and_wait_range+0xb1/0x140
ext4_sync_file+0x1aa/0xca0
vfs_fsync_range+0xfb/0x260
do_fsync+0x48/0xa0
[...]
==================================================================
Above issue may happen as follows:
-------------------------------------
do_fsync
vfs_fsync_range
ext4_sync_file
file_write_and_wait_range
__filemap_fdatawrite_range
do_writepages
ext4_writepages
mpage_map_and_submit_extent
mpage_map_one_extent
ext4_map_blocks
ext4_mb_new_blocks
ext4_mb_normalize_request
>>> start + size <= ac->ac_o_ex.fe_logical
ext4_mb_regular_allocator
ext4_mb_simple_scan_group
ext4_mb_use_best_found
ext4_mb_new_preallocation
ext4_mb_new_inode_pa
ext4_mb_use_inode_pa
>>> set ac->ac_b_ex.fe_len <= 0
ext4_mb_mark_diskspace_used
>>> BUG_ON(ac->ac_b_ex.fe_len <= 0);
we can easily reproduce this problem with the following commands:
`fallocate -l100M disk`
`mkfs.ext4 -b 1024 -g 256 disk`
`mount disk /mnt`
`fsstress -d /mnt -l 0 -n 1000 -p 1`
The size must be smaller than or equal to EXT4_BLOCKS_PER_GROUP.
Therefore, "start + size <= ac->ac_o_ex.fe_logical" may occur
when the size is truncated. So start should be the start position of
the group where ac_o_ex.fe_logical is located after alignment.
In addition, when the value of fe_logical or EXT4_BLOCKS_PER_GROUP
is very large, the value calculated by start_off is more accurate.
Cc: stable@kernel.org
Fixes: cd648b8a8fd5 ("ext4: trim allocation requests to group size")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Ritesh Harjani <ritesh.list@gmail.com>
Link: https://lore.kernel.org/r/20220528110017.354175-2-libaokun1@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
| -rw-r--r-- | fs/ext4/mballoc.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index 9f12f29bc346..4d3740fdff90 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -4104,6 +4104,15 @@ ext4_mb_normalize_request(struct ext4_allocation_context *ac, size = size >> bsbits; start = start_off >> bsbits; + /* + * For tiny groups (smaller than 8MB) the chosen allocation + * alignment may be larger than group size. Make sure the + * alignment does not move allocation to a different group which + * makes mballoc fail assertions later. + */ + start = max(start, rounddown(ac->ac_o_ex.fe_logical, + (ext4_lblk_t)EXT4_BLOCKS_PER_GROUP(ac->ac_sb))); + /* don't cover already allocated blocks in selected range */ if (ar->pleft && start <= ar->lleft) { size -= ar->lleft + 1 - start; |