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iomap/gfs2: Get page in page_prepare handler

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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: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
This commit is contained in:
Andreas Gruenbacher 2023-01-15 08:49:12 -08:00 committed by Darrick J. Wong
parent 98321b5139
commit 9060bc4d3a
3 changed files with 24 additions and 23 deletions
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21
fs/gfs2/bmap.c
View File

@ -956,15 +956,25 @@ hole_found:
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);

17
fs/iomap/buffered-io.c
View File

@ -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;
}
folio = iomap_get_folio(iter, pos);
if (IS_ERR(folio)) {
__iomap_put_folio(iter, pos, 0, NULL);
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))
return PTR_ERR(folio);
}
/*
* Now we have a locked folio, before we do anything with it we need to

9
include/linux/iomap.h
View File

@ -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);