Now, btrfs-progs has a kernel scrub equivalent.
A new option, --offline is added to "btrfs scrub start".
If --offline is given, btrfs scrub will just act like kernel scrub, to
check every copy of extent and do a report on corrupted data and if it's
recoverable.
The advantage compare to kernel scrub is:
1) No race
Unlike kernel scrub, which is done in parallel, offline scrub is done
by a single thread.
Although it may be slower than kernel one, it's safer and no false
alert.
2) Correctness
Kernel has a known bug (fix submitted) which will recovery RAID5/6
data but screw up P/Q, due to the hardness coding in kernel.
While in btrfs-progs, no page, (almost) no memory size limit, we're
can focus on the scrub, and make things easier.
New offline scrub can detect and report P/Q corruption with
recoverability report, while kernel will only report data stripe error.
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: Su <suy.fnst@cn.fujitsu.com>
Signed-off-by: Gu Jinxiang <gujx@cn.fujitsu.com>
Introduce new function, scrub_one_block_group(), to scrub a block group.
For Single/DUP/RAID0/RAID1/RAID10, we use old mirror number based
map_block, and check extent by extent.
For parity based profile (RAID5/6), we use new map_block_v2() and check
full stripe by full stripe.
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: Gu Jinxiang <gujx@cn.fujitsu.com>
Introduce a new function, scrub_one_full_stripe(), to check a full
stripe.
It handles the full stripe scrub in the following steps:
0) Check if we need to check full stripe
If full stripe contains no extent, why waste our CPU and IO?
1) Read out full stripe
Then we know how many devices are missing or have read error.
If out of repair, then exit
If have missing device or have read error, try recover here.
2) Check data stripe against csum
We add data stripe with csum error as corrupted stripe, just like
dev missing or read error.
Then recheck if csum mismatch is still below tolerance.
Finally we check the full stripe using 2 factors only:
A) If the full stripe go through recover ever
B) If the full stripe has csum error
Combine factor A and B we get:
1) A && B: Recovered, csum mismatch
Screwed up totally
2) A && !B: Recovered, csum match
Recoverable, data corrupted but P/Q is good to recover
3) !A && B: Not recovered, csum mismatch
Try to recover corrupted data stripes
If recovered csum match, then recoverable
Else, screwed up
4) !A && !B: Not recovered, no csum mismatch
Best case, just check if P/Q matches.
If P/Q matches, everything is good
Else, just P/Q is screwed up, still recoverable.
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Introduce a internal helper, write_full_stripe() to calculate P/Q and
write the whole full stripe.
This is useful to recover RAID56 stripes.
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Introduce function, recover_from_parities(), to recover data stripes.
It just wraps raid56_recov() with extra check functions to
scrub_full_stripe structure.
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Introduce new function, verify_parities(), to check whether parities match
with full stripe, whose data stripes match with their csum.
Caller should fill the scrub_full_stripe structure properly before
calling this function.
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: Gu Jinxiang <gujx@cn.fujitsu.com>
Introduce new function, scrub_one_data_stripe(), to check all data and
tree blocks inside the data stripe.
This function will not try to recovery any error, but only check if any
data/tree blocks has mismatch csum.
If data missing csum, which is completely valid for case like nodatasum,
it will just record it, but not report as error.
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: Gu Jinxiang <gujx@cn.fujitsu.com>
Introduce a new function, scrub_one_extent(), as a wrapper to check one
mirror-based extent.
It will accept a btrfs_path parameter @path, which must point to a
META/EXTENT_ITEM.
And @start, @len, which must be a subset of META/EXTENT_ITEM.
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: Gu Jinxiang <gujx@cn.fujitsu.com>
Introduce new function, check/recover_data_mirror(), to check and recover
mirror based data blocks.
Unlike tree block, data blocks must be recovered sector by sector, so we
introduced corrupted_bitmap for check and recover.
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: Su Yue <suy.fnst@cn.fujitsu.com>
Signed-off-by: Gu Jinxiang <gujx@cn.fujitsu.com>
Introduce new functions, check/recover_tree_mirror(), to check and
recover mirror-based tree blocks (Single/DUP/RAID0/1/10).
check_tree_mirror() can also be used on in-memory tree blocks using @data
parameter.
This is very handy for RAID5/6 case, either checking the data stripe
tree block by @bytenr and 0 as @mirror, or using @data parameter for
recovered in-memory data.
While recover_tree_mirror() is only used for mirror-based profiles, as
RAID56 recovery is done by stripe unit, not mirror unit.
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: Gu Jinxiang <gujx@cn.fujitsu.com>
Introuduce new local structures, scrub_full_stripe and scrub_stripe, for
incoming offline RAID56 scrub support.
For pure stripe/mirror based profiles, like raid0/1/10/dup/single, we
will follow the original bytenr and mirror number based iteration, so
they don't need any extra structures for these profiles.
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: Gu Jinxiang <gujx@cn.fujitsu.com>
Separate every command group into its own file (cmds_<group>.c) and
rearrange includes. Remove btrfs_cmds.c.
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
