From: Qu Wenruo wqu@suse.com
[ Upstream commit 54df8b80cc63aa0f22c4590cad11542731ed43ff ]
[BUG] When a scrub failed immediately without any byte scrubbed, the returned btrfs_scrub_progress::last_physical will always be 0, even if there is a non-zero @start passed into btrfs_scrub_dev() for resume cases.
This will reset the progress and make later scrub resume start from the beginning.
[CAUSE] The function btrfs_scrub_dev() accepts a @progress parameter to copy its updated progress to the caller, there are cases where we either don't touch progress::last_physical at all or copy 0 into last_physical:
- last_physical not updated at all If some error happened before scrubbing any super block or chunk, we will not copy the progress, leaving the @last_physical untouched.
E.g. failed to allocate @sctx, scrubbing a missing device or even there is already a running scrub and so on.
All those cases won't touch @progress at all, resulting the last_physical untouched and will be left as 0 for most cases.
- Error out before scrubbing any bytes In those case we allocated @sctx, and sctx->stat.last_physical is all zero (initialized by kvzalloc()). Unfortunately some critical errors happened during scrub_enumerate_chunks() or scrub_supers() before any stripe is really scrubbed.
In that case although we will copy sctx->stat back to @progress, since no byte is really scrubbed, last_physical will be overwritten to 0.
[FIX] Make sure the parameter @progress always has its @last_physical member updated to @start parameter inside btrfs_scrub_dev().
At the very beginning of the function, set @progress->last_physical to @start, so that even if we error out without doing progress copying, last_physical is still at @start.
Then after we got @sctx allocated, set sctx->stat.last_physical to @start, this will make sure even if we didn't get any byte scrubbed, at the progress copying stage the @last_physical is not left as zero.
This should resolve the resume progress reset problem.
Signed-off-by: Qu Wenruo wqu@suse.com Reviewed-by: David Sterba dsterba@suse.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Sasha Levin sashal@kernel.org ---
LLM Generated explanations, may be completely bogus:
fs/btrfs/scrub.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c index ba20d9286a340..cff67ed630196 100644 --- a/fs/btrfs/scrub.c +++ b/fs/btrfs/scrub.c @@ -3039,6 +3039,10 @@ int btrfs_scrub_dev(struct btrfs_fs_info *fs_info, u64 devid, u64 start, unsigned int nofs_flag; bool need_commit = false;
+ /* Set the basic fallback @last_physical before we got a sctx. */ + if (progress) + progress->last_physical = start; + if (btrfs_fs_closing(fs_info)) return -EAGAIN;
@@ -3057,6 +3061,7 @@ int btrfs_scrub_dev(struct btrfs_fs_info *fs_info, u64 devid, u64 start, sctx = scrub_setup_ctx(fs_info, is_dev_replace); if (IS_ERR(sctx)) return PTR_ERR(sctx); + sctx->stat.last_physical = start;
ret = scrub_workers_get(fs_info); if (ret)