From: Pankaj Raghav <p.raghav@xxxxxxxxxxx>
iomap_dio_zero() will pad a fs block with zeroes if the direct IO size
< fs block size. iomap_dio_zero() has an implicit assumption that fs block
size < page_size. This is true for most filesystems at the moment.
If the block size > page size (Large block sizes)[1], this will send the
contents of the page next to zero page(as len > PAGE_SIZE) to the
underlying block device, causing FS corruption.
iomap is a generic infrastructure and it should not make any assumptions
about the fs block size and the page size of the system.
Fixes: db074436f421 ("iomap: move the direct IO code into a separate file")
Signed-off-by: Pankaj Raghav <p.raghav@xxxxxxxxxxx>
[1] https://lore.kernel.org/lkml/20230915183848.1018717-1-kernel@xxxxxxxxxxxxxxxx/
---
I had initially planned on sending this as a part of LBS patches but I
think this can go as a standalone patch as it is a generic fix to iomap.
@Dave chinner This fixes the corruption issue you were seeing in
generic/091 for bs=64k in [2]
[2] https://lore.kernel.org/lkml/ZQfbHloBUpDh+zCg@xxxxxxxxxxxxxxxxxxx/
fs/iomap/direct-io.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
index bcd3f8cf5ea4..04f6c5548136 100644
--- a/fs/iomap/direct-io.c
+++ b/fs/iomap/direct-io.c
@@ -239,14 +239,23 @@ static void iomap_dio_zero(const struct iomap_iter *iter, struct iomap_dio *dio,
struct page *page = ZERO_PAGE(0);
struct bio *bio;
- bio = iomap_dio_alloc_bio(iter, dio, 1, REQ_OP_WRITE | REQ_SYNC | REQ_IDLE);
+ WARN_ON_ONCE(len > (BIO_MAX_VECS * PAGE_SIZE));
+
+ bio = iomap_dio_alloc_bio(iter, dio, BIO_MAX_VECS,
+ REQ_OP_WRITE | REQ_SYNC | REQ_IDLE);
fscrypt_set_bio_crypt_ctx(bio, inode, pos >> inode->i_blkbits,
GFP_KERNEL);
+
bio->bi_iter.bi_sector = iomap_sector(&iter->iomap, pos);
bio->bi_private = dio;
bio->bi_end_io = iomap_dio_bio_end_io;
- __bio_add_page(bio, page, len, 0);
+ while (len) {
+ unsigned int io_len = min_t(unsigned int, len, PAGE_SIZE);
+
+ __bio_add_page(bio, page, io_len, 0);
+ len -= io_len;
+ }
iomap_dio_submit_bio(iter, dio, bio, pos);
}
base-commit: 05d3ef8bba77c1b5f98d941d8b2d4aeab8118ef1
--
2.40.1
