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iomap: use largest_zero_folio() in iomap_dio_zero()

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iomap_dio_zero() uses a custom allocated memory of zeroes for padding
zeroes. This was a temporary solution until there was a way to request a
zero folio that was greater than the PAGE_SIZE.

Use largest_zero_folio() function instead of using the custom allocated
memory of zeroes. There is no guarantee from largest_zero_folio()
function that it will always return a PMD sized folio. Adapt the code so
that it can also work if largest_zero_folio() returns a ZERO_PAGE.

Signed-off-by: Pankaj Raghav <p.raghav@samsung.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
Pankaj Raghav
2025-08-14 16:21:37 +02:00
committed by Christian Brauner
parent b2c43efc3c
commit 10436adf9d
1 changed files with 15 additions and 23 deletions
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38
fs/iomap/direct-io.c
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@@ -24,13 +24,6 @@
#define IOMAP_DIO_WRITE (1U << 30)
#define IOMAP_DIO_DIRTY (1U << 31)
/*
* Used for sub block zeroing in iomap_dio_zero()
*/
#define IOMAP_ZERO_PAGE_SIZE (SZ_64K)
#define IOMAP_ZERO_PAGE_ORDER (get_order(IOMAP_ZERO_PAGE_SIZE))
static struct page *zero_page;
struct iomap_dio {
struct kiocb *iocb;
const struct iomap_dio_ops *dops;
@@ -285,24 +278,35 @@ static int iomap_dio_zero(const struct iomap_iter *iter, struct iomap_dio *dio,
{
struct inode *inode = file_inode(dio->iocb->ki_filp);
struct bio *bio;
struct folio *zero_folio = largest_zero_folio();
int nr_vecs = max(1, i_blocksize(inode) / folio_size(zero_folio));
if (!len)
return 0;
/*
* Max block size supported is 64k
* This limit shall never be reached as most filesystems have a
* maximum blocksize of 64k.
*/
if (WARN_ON_ONCE(len > IOMAP_ZERO_PAGE_SIZE))
if (WARN_ON_ONCE(nr_vecs > BIO_MAX_VECS))
return -EINVAL;
bio = iomap_dio_alloc_bio(iter, dio, 1, REQ_OP_WRITE | REQ_SYNC | REQ_IDLE);
bio = iomap_dio_alloc_bio(iter, dio, nr_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, zero_page, len, 0);
while (len > 0) {
unsigned int io_len = min(len, folio_size(zero_folio));
bio_add_folio_nofail(bio, zero_folio, io_len, 0);
len -= io_len;
}
iomap_dio_submit_bio(iter, dio, bio, pos);
return 0;
}
@@ -825,15 +829,3 @@ iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
return iomap_dio_complete(dio);
}
EXPORT_SYMBOL_GPL(iomap_dio_rw);
static int __init iomap_dio_init(void)
{
zero_page = alloc_pages(GFP_KERNEL | __GFP_ZERO,
IOMAP_ZERO_PAGE_ORDER);
if (!zero_page)
return -ENOMEM;
return 0;
}
fs_initcall(iomap_dio_init);