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iomap: fix incorrect did_zero setting in iomap_zero_iter()

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The did_zero output parameter was unconditionally set after the loop,
which is incorrect. It should only be set when the zeroing operation
actually completes, not when IOMAP_F_STALE is set or when
IOMAP_F_FOLIO_BATCH is set but !folio causes the loop to break early,
or when iomap_iter_advance() returns an error.

This causes did_zero to be incorrectly set when zeroing a clean
unwritten extent because the loop exits early without actually zeroing
any data.

Fix it by using a local variable to track whether any folio was actually
zeroed, and only set did_zero after the loop if zeroing happened.

Fixes: 98eb8d9502 ("iomap: set did_zero to true when zeroing successfully")
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Link: https://patch.msgid.link/20260714082325.325163-4-yi.zhang@huaweicloud.com
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
This commit is contained in:
Zhang Yi 2026-07-14 16:23:23 +08:00 committed by Christian Brauner
parent 562d192c43
commit 7a6fd6b21d
1 changed files with 6 additions and 2 deletions
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8
fs/iomap/buffered-io.c
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@ -1625,6 +1625,7 @@ static int iomap_zero_iter(struct iomap_iter *iter, bool *did_zero,
const struct iomap_write_ops *write_ops)
{
u64 bytes = iomap_length(iter);
bool zeroed = false;
int status;
do {
@ -1645,6 +1646,8 @@ static int iomap_zero_iter(struct iomap_iter *iter, bool *did_zero,
/* a NULL folio means we're done with a folio batch */
if (!folio) {
status = iomap_iter_advance_full(iter);
if (status)
return status;
break;
}
@ -1655,6 +1658,7 @@ static int iomap_zero_iter(struct iomap_iter *iter, bool *did_zero,
bytes);
folio_zero_range(folio, offset, bytes);
zeroed = true;
folio_mark_accessed(folio);
ret = iomap_write_end(iter, bytes, bytes, folio);
@ -1664,10 +1668,10 @@ static int iomap_zero_iter(struct iomap_iter *iter, bool *did_zero,
status = iomap_iter_advance(iter, bytes);
if (status)
break;
return status;
} while ((bytes = iomap_length(iter)) > 0);
if (did_zero)
if (did_zero && zeroed)
*did_zero = true;
return status;
}