Commit 8dc00053 authored by John Garry's avatar John Garry Committed by Long Li
Browse files

fs: iomap: Atomic write support 

maillist inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I9VTE3
CVE: NA

Reference: https://lore.kernel.org/all/20240326133813.3224593-1-john.g.garry@oracle.com/



--------------------------------

Support atomic writes by producing a single BIO with REQ_ATOMIC flag set.

We rely on the FS to guarantee extent alignment, such that an atomic write
should never straddle two or more extents. The FS should also check for
validity of an atomic write length/alignment.

Signed-off-by: default avatarJohn Garry <john.g.garry@oracle.com>
Signed-off-by: default avatarLong Li <leo.lilong@huawei.com>
parent 0bf11106

fs/iomap/direct-io.c

+9 −0
Original line number Diff line number Diff line
@@ -234,6 +234,7 @@ static loff_t 
iomap_dio_bio_actor(struct inode *inode, loff_t pos, loff_t length,

		struct iomap_dio *dio, struct iomap *iomap)

{

	bool is_atomic = dio->iocb->ki_flags & IOCB_ATOMIC;

	unsigned int blkbits = blksize_bits(bdev_logical_block_size(iomap->bdev));

	unsigned int zeroing_size, pad;

	unsigned int align = iov_iter_alignment(dio->submit.iter);
@@ -323,8 +324,16 @@ iomap_dio_bio_actor(struct inode *inode, loff_t pos, loff_t length, 
		}



		n = bio->bi_iter.bi_size;

		if (is_atomic && (n != orig_count)) {

			/* This bio should have covered the complete length */

			ret = -EINVAL;

			bio_put(bio);

			goto out;

		}

		if (dio->flags & IOMAP_DIO_WRITE) {

			bio->bi_opf = REQ_OP_WRITE | REQ_SYNC | REQ_IDLE;

			if (is_atomic)

				bio->bi_opf |= REQ_ATOMIC;

			if (use_fua)

				bio->bi_opf |= REQ_FUA;

			else