[BUG]
Sometimes test case btrfs/012 fails randomly, with the failure to read a
symlink:
QA output created by 012
Checking converted btrfs against the original one:
-OK
+readlink: Structure needs cleaning
Checking saved ext2 image against the original one:
OK
Furthermore, this will trigger a kernel error message:
BTRFS critical (device dm-2): regular/prealloc extent found for non-regular inode 133081
[CAUSE]
For that specific inode 133081, the tree dump looks like this:
item 127 key (133081 INODE_ITEM 0) itemoff 40984 itemsize 160
generation 1 transid 1 size 4095 nbytes 4096
block group 0 mode 120777 links 1 uid 0 gid 0 rdev 0
sequence 0 flags 0x0(none)
item 128 key (133081 INODE_REF 133080) itemoff 40972 itemsize 12
index 2 namelen 2 name: l3
item 129 key (133081 EXTENT_DATA 0) itemoff 40919 itemsize 53
generation 4 type 1 (regular)
extent data disk byte 2147483648 nr 38080512
extent data offset 37974016 nr 4096 ram 38080512
extent compression 0 (none)
Note that, the symlink inode size is 4095 at the max size (PATH_MAX,
removing the terminating NUL).
But the nbytes is 4096, exactly matching the sector size of the btrfs.
Thus it results the creation of a regular extent, but for btrfs we do
not accept a symlink with a regular/preallocated extent, thus kernel
rejects such read and failed the readlink call.
The root cause is in the convert code, where for symlinks we always
create a data extent with its size + 1, causing the above problem.
I guess the original code is to handle the terminating NUL, but in btrfs
we never need to store the terminating NUL for inline extents nor
file names.
Thus this pitfall in btrfs-convert leads to the above invalid data
extent and fail the test case.
[FIX]
- Fix the ext2 and reiserfs symbolic link creation code
To remove the terminating NUL.
- Add extra checks for the size of a symbolic link
Btrfs has extra limits on the size of a symbolic link, as btrfs must
store symbolic link targets as inlined extents.
This means for 4K node sized btrfs, the size limit is smaller than the
usual PATH_MAX - 1 (only around 4000 bytes instead of 4095).
So for certain nodesize, some filesystems can not be converted to
btrfs.
(this should be rare, because the default nodesize is 16K already)
- Split the symbolic link and inline data extent size checks
For symbolic links the real limit is PATH_MAX - 1 (removing the
terminating NUL), but for inline data extents the limit is
sectorsize - 1, which can be different from 4096 - 1 (e.g. 64K sector
size).
Pull-request: #884
Signed-off-by: Qu Wenruo <wqu@suse.com>
This patch would modify btrfs_csum_file_block() to handle csum type
other than the one used in the current fs.
The new data checksum would use a different objectid (-13) to
distinguish with the existing one (-10).
This needs to change tree-checker to skip the item size checks,
since new csum can be larger than the original csum.
After this stage, the resulted csum tree would look like this:
item 0 key (CSUM_CHANGE EXTENT_CSUM 13631488) itemoff 8091 itemsize 8192
range start 13631488 end 22020096 length 8388608
item 1 key (EXTENT_CSUM EXTENT_CSUM 13631488) itemoff 7067 itemsize 1024
range start 13631488 end 14680064 length 1048576
Note the itemsize is 8 times the original one, as the original csum is
CRC32, while target csum is SHA256, which is 8 times the size.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This patch syncs file-item.h into btrfs-progs. This carries with it an
API change for btrfs_del_csums, which takes a root argument in the
kernel, so all callsites have been updated accordingly.
I didn't sync file-item.c because it carries with it a bunch of bio
related helpers which are difficult to adapt to the kernel.
Additionally there's a few helpers in the local copy of file-item.c that
aren't in the kernel that are required for different tools.
This requires more cleanups in both the kernel and progs in order to
sync file-item.c, so for now just do file-item.h in order to pull things
out of ctree.h.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Qu Wenruo
David Sterba
Josef Bacik