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bcachefs: Fix silent short reads in data read retry path

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__bch2_read, before calling __bch2_read_extent(), sets bvec_iter.bi_size
to "the size we can read from the current extent" with a swap, and
restores it to "the size for the total read" after the read_extent call
with another swap.

But we neglected to do the restore before the "if (ret) goto err;" -
which is a problem if we're retrying those errors.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet 2025-03-24 11:51:01 -04:00
parent 5af61dbd96
commit 3ba0240a87
3 changed files with 7 additions and 4 deletions
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2
fs/bcachefs/fs-io-buffered.c
View File

@ -225,11 +225,11 @@ static void bchfs_read(struct btree_trans *trans,
bch2_read_extent(trans, rbio, iter.pos,
data_btree, k, offset_into_extent, flags);
swap(rbio->bio.bi_iter.bi_size, bytes);
if (flags & BCH_READ_last_fragment)
break;
swap(rbio->bio.bi_iter.bi_size, bytes);
bio_advance(&rbio->bio, bytes);
err:
if (ret &&

3
fs/bcachefs/io_read.c
View File

@ -1322,13 +1322,14 @@ int __bch2_read(struct btree_trans *trans, struct bch_read_bio *rbio,
ret = __bch2_read_extent(trans, rbio, bvec_iter, iter.pos,
data_btree, k,
offset_into_extent, failed, flags, -1);
swap(bvec_iter.bi_size, bytes);
if (ret)
goto err;
if (flags & BCH_READ_last_fragment)
break;
swap(bvec_iter.bi_size, bytes);
bio_advance_iter(&rbio->bio, &bvec_iter, bytes);
err:
if (ret == -BCH_ERR_data_read_retry_csum_err_maybe_userspace)

6
fs/bcachefs/io_read.h
View File

@ -137,8 +137,10 @@ static inline void bch2_read_extent(struct btree_trans *trans,
enum btree_id data_btree, struct bkey_s_c k,
unsigned offset_into_extent, unsigned flags)
{
__bch2_read_extent(trans, rbio, rbio->bio.bi_iter, read_pos,
data_btree, k, offset_into_extent, NULL, flags, -1);
int ret = __bch2_read_extent(trans, rbio, rbio->bio.bi_iter, read_pos,
data_btree, k, offset_into_extent, NULL, flags, -1);
/* __bch2_read_extent only returns errors if BCH_READ_in_retry is set */
WARN(ret, "unhandled error from __bch2_read_extent()");
}
int __bch2_read(struct btree_trans *, struct bch_read_bio *, struct bvec_iter,