Unverified Commit 943bc088 authored by Zhang Yi's avatar Zhang Yi Committed by Christian Brauner
Browse files

iomap: don't increase i_size if it's not a write operation 



Increase i_size in iomap_zero_range() and iomap_unshare_iter() is not
needed, the caller should handle it. Especially, when truncate partial
block, we should not increase i_size beyond the new EOF here. It doesn't
affect xfs and gfs2 now because they set the new file size after zero
out, it doesn't matter that a transient increase in i_size, but it will
affect ext4 because it set file size before truncate. So move the i_size
updating logic to iomap_write_iter().

Signed-off-by: default avatarZhang Yi <yi.zhang@huawei.com>
Link: https://lore.kernel.org/r/20240320110548.2200662-7-yi.zhang@huaweicloud.com


Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarDarrick J. Wong <djwong@kernel.org>
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent 89c6c1d9

fs/iomap/buffered-io.c

+25 −25
Original line number Diff line number Diff line
@@ -875,32 +875,13 @@ static size_t iomap_write_end(struct iomap_iter *iter, loff_t pos, size_t len, 
		size_t copied, struct folio *folio)

{

	const struct iomap *srcmap = iomap_iter_srcmap(iter);

	loff_t old_size = iter->inode->i_size;

	size_t ret;



	if (srcmap->type == IOMAP_INLINE) {

		ret = iomap_write_end_inline(iter, folio, pos, copied);

	} else if (srcmap->flags & IOMAP_F_BUFFER_HEAD) {

		ret = block_write_end(NULL, iter->inode->i_mapping, pos, len,

	if (srcmap->type == IOMAP_INLINE)

		return iomap_write_end_inline(iter, folio, pos, copied);

	if (srcmap->flags & IOMAP_F_BUFFER_HEAD)

		return block_write_end(NULL, iter->inode->i_mapping, pos, len,

				       copied, &folio->page, NULL);

	} else {

		ret = __iomap_write_end(iter->inode, pos, len, copied, folio);

	}



	/*

	 * Update the in-memory inode size after copying the data into the page

	 * cache.  It's up to the file system to write the updated size to disk,

	 * preferably after I/O completion so that no stale data is exposed.

	 */

	if (pos + ret > old_size) {

		i_size_write(iter->inode, pos + ret);

		iter->iomap.flags |= IOMAP_F_SIZE_CHANGED;

	}

	__iomap_put_folio(iter, pos, ret, folio);



	if (old_size < pos)

		pagecache_isize_extended(iter->inode, old_size, pos);

	return ret;

	return __iomap_write_end(iter->inode, pos, len, copied, folio);

}



static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i)
@@ -915,6 +896,7 @@ static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i) 


	do {

		struct folio *folio;

		loff_t old_size;

		size_t offset;		/* Offset into folio */

		size_t bytes;		/* Bytes to write to folio */

		size_t copied;		/* Bytes copied from user */
@@ -964,6 +946,22 @@ static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i) 
		copied = copy_folio_from_iter_atomic(folio, offset, bytes, i);

		status = iomap_write_end(iter, pos, bytes, copied, folio);



		/*

		 * Update the in-memory inode size after copying the data into

		 * the page cache.  It's up to the file system to write the

		 * updated size to disk, preferably after I/O completion so that

		 * no stale data is exposed.  Only once that's done can we

		 * unlock and release the folio.

		 */

		old_size = iter->inode->i_size;

		if (pos + status > old_size) {

			i_size_write(iter->inode, pos + status);

			iter->iomap.flags |= IOMAP_F_SIZE_CHANGED;

		}

		__iomap_put_folio(iter, pos, status, folio);



		if (old_size < pos)

			pagecache_isize_extended(iter->inode, old_size, pos);

		if (status < bytes)

			iomap_write_failed(iter->inode, pos + status,

					   bytes - status);
@@ -1336,6 +1334,7 @@ static loff_t iomap_unshare_iter(struct iomap_iter *iter) 
			bytes = folio_size(folio) - offset;



		bytes = iomap_write_end(iter, pos, bytes, bytes, folio);

		__iomap_put_folio(iter, pos, bytes, folio);

		if (WARN_ON_ONCE(bytes == 0))

			return -EIO;
@@ -1400,6 +1399,7 @@ static loff_t iomap_zero_iter(struct iomap_iter *iter, bool *did_zero) 
		folio_mark_accessed(folio);



		bytes = iomap_write_end(iter, pos, bytes, bytes, folio);

		__iomap_put_folio(iter, pos, bytes, folio);

		if (WARN_ON_ONCE(bytes == 0))

			return -EIO;