Commit 9060bc4d authored by Andreas Gruenbacher's avatar Andreas Gruenbacher Committed by Darrick J. Wong
Browse files

iomap/gfs2: Get page in page_prepare handler 



Change the iomap ->page_prepare() handler to get and return a locked
folio instead of doing that in iomap_write_begin().  This allows to
recover from out-of-memory situations in ->page_prepare(), which
eliminates the corresponding error handling code in iomap_write_begin().
The ->put_folio() handler now also isn't called with NULL as the folio
value anymore.

Filesystems are expected to use the iomap_get_folio() helper for getting
locked folios in their ->page_prepare() handlers.

Signed-off-by: default avatarAndreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: default avatarDarrick J. Wong <djwong@kernel.org>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarDarrick J. Wong <djwong@kernel.org>
parent 98321b51

fs/gfs2/bmap.c

+13 −8
Original line number Diff line number Diff line
@@ -956,15 +956,25 @@ static int __gfs2_iomap_get(struct inode *inode, loff_t pos, loff_t length, 
	goto out;

}



static int gfs2_iomap_page_prepare(struct inode *inode, loff_t pos,

				   unsigned len)

static struct folio *

gfs2_iomap_page_prepare(struct iomap_iter *iter, loff_t pos, unsigned len)

{

	struct inode *inode = iter->inode;

	unsigned int blockmask = i_blocksize(inode) - 1;

	struct gfs2_sbd *sdp = GFS2_SB(inode);

	unsigned int blocks;

	struct folio *folio;

	int status;



	blocks = ((pos & blockmask) + len + blockmask) >> inode->i_blkbits;

	return gfs2_trans_begin(sdp, RES_DINODE + blocks, 0);

	status = gfs2_trans_begin(sdp, RES_DINODE + blocks, 0);

	if (status)

		return ERR_PTR(status);



	folio = iomap_get_folio(iter, pos);

	if (IS_ERR(folio))

		gfs2_trans_end(sdp);

	return folio;

}



static void gfs2_iomap_put_folio(struct inode *inode, loff_t pos,
@@ -974,11 +984,6 @@ static void gfs2_iomap_put_folio(struct inode *inode, loff_t pos, 
	struct gfs2_inode *ip = GFS2_I(inode);

	struct gfs2_sbd *sdp = GFS2_SB(inode);



	if (!folio) {

		gfs2_trans_end(sdp);

		return;

	}



	if (!gfs2_is_stuffed(ip))

		gfs2_page_add_databufs(ip, &folio->page, offset_in_page(pos),

				       copied);

fs/iomap/buffered-io.c

+6 −11
Original line number Diff line number Diff line
@@ -609,7 +609,7 @@ static void __iomap_put_folio(struct iomap_iter *iter, loff_t pos, size_t ret, 


	if (page_ops && page_ops->put_folio) {

		page_ops->put_folio(iter->inode, pos, ret, folio);

	} else if (folio) {

	} else {

		folio_unlock(folio);

		folio_put(folio);

	}
@@ -642,17 +642,12 @@ static int iomap_write_begin(struct iomap_iter *iter, loff_t pos, 
	if (!mapping_large_folio_support(iter->inode->i_mapping))

		len = min_t(size_t, len, PAGE_SIZE - offset_in_page(pos));



	if (page_ops && page_ops->page_prepare) {

		status = page_ops->page_prepare(iter->inode, pos, len);

		if (status)

			return status;

	}



	if (page_ops && page_ops->page_prepare)

		folio = page_ops->page_prepare(iter, pos, len);

	else

		folio = iomap_get_folio(iter, pos);

	if (IS_ERR(folio)) {

		__iomap_put_folio(iter, pos, 0, NULL);

	if (IS_ERR(folio))

		return PTR_ERR(folio);

	}



	/*

	 * Now we have a locked folio, before we do anything with it we need to

include/linux/iomap.h

+5 −4
Original line number Diff line number Diff line
@@ -13,6 +13,7 @@ 
struct address_space;

struct fiemap_extent_info;

struct inode;

struct iomap_iter;

struct iomap_dio;

struct iomap_writepage_ctx;

struct iov_iter;
@@ -131,12 +132,12 @@ static inline bool iomap_inline_data_valid(const struct iomap *iomap) 
 * associated with them.

 *

 * When page_prepare succeeds, put_folio will always be called to do any

 * cleanup work necessary.  In that put_folio call, @folio will be NULL if the

 * associated folio could not be obtained.  When folio is not NULL, put_folio

 * is responsible for unlocking and putting the folio.

 * cleanup work necessary.  put_folio is responsible for unlocking and putting

 * @folio.

 */

struct iomap_page_ops {

	int (*page_prepare)(struct inode *inode, loff_t pos, unsigned len);

	struct folio *(*page_prepare)(struct iomap_iter *iter, loff_t pos,

			unsigned len);

	void (*put_folio)(struct inode *inode, loff_t pos, unsigned copied,

			struct folio *folio);