[BUG]
When compiling the devel branch with commit fb8f05e40b458
("btrfs-progs: check: Make repair_imode_common() handle inodes in
subvolume trees"), the following warning will be reported:
check/mode-common.c: In function ‘detect_imode’:
check/mode-common.c|1071 col 23| warning: ‘imode’ may be used uninitialized in this function [-Wmaybe-uninitialized]
1071 | *imode_ret = (imode | 0700);
| ~~~~~~~^~~~~~~
This only occurs for regular build. If compiled with D=1, the warning
just disappears.
[CAUSE]
Looks like a bug in gcc optimization.
The code will only set @imode_ret when @found is true.
And for every "found = true" assignment we have assigned @imode.
So this is just a false alert.
[FIX]
I hope I can fix the problem of GCC, but obviously I can't (at least for
now).
So let's assign an initial value 0 to @imode to suppress the false
alert.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
To make original mode to repair imode error in subvolume trees, this
patch will do:
- Remove the show-stopper checks for root->objectid.
Now repair_imode_original() will accept inodes in subvolume trees.
- Export detect_imode() for original mode
Due to the call requirement, original mode must use an existing trans
handler to do the repair, thus we need to re-implement most of the
work done in repair_imode_common().
- Make repair_imode_original() to use detect_imode().
- Free the path after reset_imode()
reset_imode() keeps the path, as lowmem mode uses path to locate its
current check position.
But for original mode, the unreleased path can cause later repair to
report warning, so we need to manually release the path.
- Update rec->imode after imode reset
So later repair depending on rec->imode can get correct value.
- Move the repair before repair_inode_nlinks()
repair_inode_nlinks() needs correct imode to add DIR_INDEX/DIR_ITEM.
So moving the repair before repair_inode_nlinks() makes the latter
repair happier.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[[PROBLEM]]
Before this patch, repair_imode_common() can only handle two types of
inodes:
- Free space cache inodes
- ROOT DIR inodes
For inodes in subvolume trees, the core complexity is how to determine
the correct imode, thus it was not implemented.
However there are more reports of incorrect imode in subvolume trees, we
need to support such fix.
[[ENHANCEMENT]]
So this patch adds a new function, detect_imode(), to detect imode for
inodes in subvolume trees. The policy here is, try our best to find a
valid imode to recovery. If no convicing info can be found, fail out.
That function will determine imode by:
1) Search for INODE_REF of the inode
If we have INODE_REF, we will then try to find DIR_ITEM/DIR_INDEX.
As long as one valid DIR_ITEM or DIR_INDEX can be found, we convert
the BTRFS_FT_* to imode, then call it a day.
This should be the most accurate way.
2) Search for DIR_INDEX/DIR_ITEM belongs to this inode
If above search fails, we falls back to locate the DIR_INDEX/DIR_ITEM
just after the INODE_ITEM.
Thus this only works for non-empty directory.
If any can be found, it's definitely a directory.
3) Search for EXTENT_DATA belongs to this inode
If EXTENT_DATA can be found, it's either REG or LNK.
Thus this only works for non-empty file or soft link.
For this case, we default to REG, as user can inspect the file to
determine if it's a file or just a path.
4) Use rdev to detect BLK/CHR
If all above fails, but INODE_ITEM has non-zero rdev, then it's either
a BLK or CHR file. Then we default to BLK.
5) Fail out if none of above methods succeeded
No educated guess to make things worse.
[[SHORTCOMING]]
The above search is not perfect, there are cases where we can't repair:
E.g. orphan empty regular inode. Since it's already orphan, it has no
INODE_REF. And it's regular empty file, it has no DIR_INDEX nor
EXTENT_DATA nor rdev. Thus we can't recover. Although for this case, it
really doesn't matter as it's already orphan and will be deleted anyway.
Furthermore, due to the DIR_ITEM/DIR_INDEX/INODE_REF repair code which
can happen before imode repair, it's possible that DIR_ITEM search code
may not be executed. If there is only DIR_ITEM remaining, repair code
will remove the DIR_ITEM completely and move the inode to lost+found,
leaving us no info to rebuild imode. If there is DIR_INDEX missing,
repair code will re-insert the DIR_INDEX, then imode repair code will go
DIR_INDEX directly.
But overall, the repair code should handle the invalid imode caused by
older kernels without problem.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Introduce a function, find_file_type(), to find filetype using info from
INODE_REF, including dir_id from key index/name from inode_ref_item.
This function will:
- Search DIR_INDEX first
DIR_INDEX is easier since there is only one item in it.
- Validate the DIR_INDEX item
If the DIR_INDEX is valid, use the filetype and call it a day.
- Search DIR_ITEM then
It needs extra iteration since it's possible to have hash collision.
- Validate the DIR_ITEM
If valid, call it a day. Or return -ENOENT;
This would be used as the primary method to determine the imode in later
imode repair code.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Since kernel is going to reject any root item which is newer than super
block generation, we need to provide a way to fix such problem in
btrfs-check.
This patch addes the ability to report and repair root generation in
lowmem mode.
This is done by cowing the root node, so we will update the root
generation along with the root node generation at commit transaction
time.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Create directory for all sources that can be used by anything that's not
rellated to a relevant kernel part, all common functions, helpers,
utilities that do not fit any other specific category.
The traditional location would be probably lib/ with all things that are
statically linked to the main binaries, but we have libbtrfs and
libbtrfsutil so this would be confusing.
Signed-off-by: David Sterba <dsterba@suse.com>
Unlike inodes in fs roots, we don't really check the inode items in root
tree, in fact we just skip everything other than ROOT_ITEM and ROOT_REF.
This makes invalid inode items sneak into root tree.
For example:
item 9 key (256 INODE_ITEM 0) itemoff 13702 itemsize 160
generation 30 transid 30 size 65536 nbytes 1507328
block group 0 mode 0 links 1 uid 0 gid 0 rdev 0
^ Should be 100600
sequence 23 flags 0x1b(NODATASUM|NODATACOW|NOCOMPRESS|PREALLOC)
atime 0.0 (1970-01-01 08:00:00)
ctime 1553491158.189771625 (2019-03-25 13:19:18)
mtime 0.0 (1970-01-01 08:00:00)
otime 0.0 (1970-01-01 08:00:00)
There is a report of such problem in the mail list.
This patch will check and repair inode items of free space cache inodes in
lowmem mode.
Since free space cache inodes doesn't have INODE_REF but still has 1
link, we can't use check_inode_item() directly.
Instead we only check the inode mode, as that's the important part.
The check and repair function: check_repair_free_space_inode() is also
exported for original mode.
Signed-off-by: Qu Wenruo <wqu@suse.com>
In root tree, we only have 2 types of inodes:
- ROOT_TREE_DIR inode
Its mode is fixed to 40755
- free space cache inodes
Its mode is fixed to 100600
This patch will add the ability to repair such inodes to lowmem mode.
For fs/subvolume tree error, at least we haven't see such corruption
yet, so we don't need to rush to fix corruption in fs trees yet.
The repair function, reset_imode() and repair_imode_common() can be
reused by later original mode patch, so it's placed in check/mode-common.c.
Signed-off-by: Qu Wenruo <wqu@suse.com>
For DIR_ITEM with mismatch hash, we could just remove the offending dir
item from the tree.
Lowmem mode will handle the rest, either re-create the correct dir_item
or move the orphan inode to lost+found.
This is especially important for old filesystems, since later kernel
introduces stricter tree-checker, which could detect such hash mismatch
and refuse to read the corrupted leaf.
With this repair ability, user could repair with 'btrfs check
--mode=lowmem --repair'.
Link: https://bugzilla.opensuse.org/show_bug.cgi?id=1111991
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Similar to the changes where strerror(errno) was converted, continue
with the remaining cases where the argument was stored in another
variable.
The savings in object size are about 4500 bytes:
$ size btrfs.old btrfs.new
text data bss dec hex filename
805055 24248 19748 849051 cf49b btrfs.old
804527 24248 19748 848523 cf28b btrfs.new
Signed-off-by: David Sterba <dsterba@suse.com>
Initialize all filed of btrfs_inode_item to zero in order to prevent
having some garbage, especially for flags field.
Signed-off-by: Misono Tomohiro <misono.tomohiro@jp.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Commit d17d6663c99c ("btrfs-progs: lowmem check: Fix regression which
screws up extent allocator") removes pin_metadata_blocks() from lowmem
repair. So we have to find another way to exclude extents which should
be occupied by existing tree blocks.
Modify pin_down_tree_blocks() and rename it to traverse_tree_blocks
for sharing code with new function exclude_metadata_blocks().
* exclude_metadata_blocks() traverses and marks extents of all tree
blocks dirty in fs_info->excluded_extents.
* cleanup_excluded_extents() is responsible for cleanup.
Export them to mode-common.h since they will be used both in original
and lowmem modes.
Signed-off-by: Su Yue <suy.fnst@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Move pin_down_tree_blocks from main.c to mode-common.c for
further patches.
And export pin_metadata_blocks to mode-common.h.
Signed-off-by: Su Yue <suy.fnst@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Under some cases the filesystem checker reports an error when it finds
checksum items for an extent that is referenced by an inode as a prealloc
extent. Such cases are not an error when the extent is actually shared
(was cloned/reflinked) with other inodes and was written through one of
those other inodes.
Example:
$ mkfs.btrfs -f /dev/sdb
$ mount /dev/sdb /mnt
$ touch /mnt/foo
$ xfs_io -c "falloc 0 256K" /mnt/foo
$ sync
$ xfs_io -c "pwrite -S 0xab 0 256K" /mnt/foo
$ touch /mnt/bar
$ xfs_io -c "reflink /mnt/foo 0 0 256K" /mnt/bar
$ xfs_io -c "fsync" /mnt/bar
<power fail>
$ mount /dev/sdb /mnt
$ umount /mnt
$ btrfs check /dev/sdc
Checking filesystem on /dev/sdb
UUID: 52d3006e-ee3b-40eb-aa21-e56253a03d39
checking extents
checking free space cache
checking fs roots
root 5 inode 257 errors 800, odd csum item
ERROR: errors found in fs roots
found 688128 bytes used, error(s) found
total csum bytes: 256
total tree bytes: 163840
total fs tree bytes: 65536
total extent tree bytes: 16384
btree space waste bytes: 138819
file data blocks allocated: 10747904
referenced 10747904
$ echo $?
1
So teach check to not report such cases as errors by checking if the
extent is shared with other inodes and if so, consider it an error the
existence of checksum items only if all those other inodes are referencing
the extent as a prealloc extent.
This case can be hit often when running the generic/475 testcase from
fstests.
A test case will follow in a separate patch.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
