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author | Josef Bacik <josef@toxicpanda.com> | 2020-02-13 10:47:31 -0500 |
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committer | David Sterba <dsterba@suse.com> | 2020-02-19 00:39:08 +0100 |
commit | b778cf962d71a0e737923d55d0432f3bd287258e (patch) | |
tree | 9bea99b4da9b5c84421d23bdeaaf5deee5e149fa /fs/btrfs | |
parent | bd727173e4432fe6cb70ba108dc1f3602c5409d7 (diff) | |
download | linux-b778cf962d71a0e737923d55d0432f3bd287258e.tar.gz |
btrfs: fix bytes_may_use underflow in prealloc error condtition
I hit the following warning while running my error injection stress testing: WARNING: CPU: 3 PID: 1453 at fs/btrfs/space-info.h:108 btrfs_free_reserved_data_space_noquota+0xfd/0x160 [btrfs] RIP: 0010:btrfs_free_reserved_data_space_noquota+0xfd/0x160 [btrfs] Call Trace: btrfs_free_reserved_data_space+0x4f/0x70 [btrfs] __btrfs_prealloc_file_range+0x378/0x470 [btrfs] elfcorehdr_read+0x40/0x40 ? elfcorehdr_read+0x40/0x40 ? btrfs_commit_transaction+0xca/0xa50 [btrfs] ? dput+0xb4/0x2a0 ? btrfs_log_dentry_safe+0x55/0x70 [btrfs] ? btrfs_sync_file+0x30e/0x420 [btrfs] ? do_fsync+0x38/0x70 ? __x64_sys_fdatasync+0x13/0x20 ? do_syscall_64+0x5b/0x1b0 ? entry_SYSCALL_64_after_hwframe+0x44/0xa9 This happens if we fail to insert our reserved file extent. At this point we've already converted our reservation from ->bytes_may_use to ->bytes_reserved. However once we break we will attempt to free everything from [cur_offset, end] from ->bytes_may_use, but our extent reservation will overlap part of this. Fix this problem by adding ins.offset (our extent allocation size) to cur_offset so we remove the actual remaining part from ->bytes_may_use. I validated this fix using my inject-error.py script python inject-error.py -o should_fail_bio -t cache_save_setup -t \ __btrfs_prealloc_file_range \ -t insert_reserved_file_extent.constprop.0 \ -r "-5" ./run-fsstress.sh where run-fsstress.sh simply mounts and runs fsstress on a disk. CC: stable@vger.kernel.org # 4.4+ Reviewed-by: Qu Wenruo <wqu@suse.com> Signed-off-by: Josef Bacik <josef@toxicpanda.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs')
-rw-r--r-- | fs/btrfs/inode.c | 16 |
1 files changed, 13 insertions, 3 deletions
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 36deef69f847..4f47ba652b31 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -9824,6 +9824,7 @@ static int __btrfs_prealloc_file_range(struct inode *inode, int mode, struct btrfs_root *root = BTRFS_I(inode)->root; struct btrfs_key ins; u64 cur_offset = start; + u64 clear_offset = start; u64 i_size; u64 cur_bytes; u64 last_alloc = (u64)-1; @@ -9858,6 +9859,15 @@ static int __btrfs_prealloc_file_range(struct inode *inode, int mode, btrfs_end_transaction(trans); break; } + + /* + * We've reserved this space, and thus converted it from + * ->bytes_may_use to ->bytes_reserved. Any error that happens + * from here on out we will only need to clear our reservation + * for the remaining unreserved area, so advance our + * clear_offset by our extent size. + */ + clear_offset += ins.offset; btrfs_dec_block_group_reservations(fs_info, ins.objectid); last_alloc = ins.offset; @@ -9937,9 +9947,9 @@ next: if (own_trans) btrfs_end_transaction(trans); } - if (cur_offset < end) - btrfs_free_reserved_data_space(inode, NULL, cur_offset, - end - cur_offset + 1); + if (clear_offset < end) + btrfs_free_reserved_data_space(inode, NULL, clear_offset, + end - clear_offset + 1); return ret; } |