bc0995297f
[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>
|
||
|---|---|---|
| .. | ||
| uapi | ||
| README.md | ||
| accessors.c | ||
| accessors.h | ||
| async-thread.c | ||
| async-thread.h | ||
| backref.c | ||
| backref.h | ||
| compression.h | ||
| ctree.c | ||
| ctree.h | ||
| delayed-ref.c | ||
| delayed-ref.h | ||
| dir-item.c | ||
| disk-io.c | ||
| disk-io.h | ||
| extent-io-tree.c | ||
| extent-io-tree.h | ||
| extent-tree.c | ||
| extent_io.c | ||
| extent_io.h | ||
| file-item.c | ||
| file-item.h | ||
| file.c | ||
| free-space-cache.c | ||
| free-space-cache.h | ||
| free-space-tree.c | ||
| free-space-tree.h | ||
| inode-item.c | ||
| inode.c | ||
| locking.c | ||
| locking.h | ||
| messages.c | ||
| messages.h | ||
| misc.h | ||
| print-tree.c | ||
| print-tree.h | ||
| root-tree.c | ||
| send.h | ||
| transaction.c | ||
| transaction.h | ||
| tree-checker.c | ||
| tree-checker.h | ||
| tree-mod-log.h | ||
| ulist.c | ||
| ulist.h | ||
| uuid-tree.c | ||
| uuid-tree.h | ||
| volumes.c | ||
| volumes.h | ||
| zoned.c | ||
| zoned.h | ||
README.md
Shared sources with kernel
Status and progress of kernel/userspace synchronization.
- accessors.c - done, local changes
- accessors.h - done, local changes
- async-thread.c - done
- async-thread.h - done
- backref.c - todo
- backref.h - todo
- compression.h - done
- ctree.c - partial
- ctree.h - partial
- delayed-ref.c - partial
- delayed-ref.h - partial
- dir-item.c - partial
- disk-io.c - todo
- disk-io.h - todo
- extent_io.c
- extent_io.h
- extent-io-tree.c - done, local changes
- extent-io-tree.h - done, local changes
- extent-tree.c - todo
- file.c - todo
- file-item.c - todo
- file-item.h - partial
- free-space-cache.c - not needed
- free-space-cache.h - not needed
- free-space-tree.c - partial
- free-space-tree.h - partial
- inode.c - todo
- inode-item.c - partial
- locking.c - done, local changes
- locking.h - done, local changes
- messages.c - done, local changes
- messages.h - done, local changes
- misc.h - done
- print-tree.c - partial, sync to kernel
- print-tree.h - partial
- root-tree.c - partial
- root-tree.h - done
- send.h - done
- transaction.c - todo
- transaction.h - partial, local changes
- tree-checker.c - partial, local changes
- tree-checker.h - partial, local changes
- tree-mod-log.h - done, local changes
- ulist.c - done
- ulist.h - done
- uuid-tree.c - partial
- uuid-tree.h - partial, local changes
- volumes.c - todo, local changes
- volumes.h - todo, local changes
- zoned.c - todo
- zoned.h - todo