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iomap: Handle memory allocation failure in readahead

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bio_alloc() can fail when we use GFP_NORETRY.  If it does, allocate
a bio large enough for a single page like mpage_readpages() does.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
This commit is contained in:
Matthew Wilcox (Oracle)
2020-04-02 09:08:53 -07:00
committed by Darrick J. Wong
parent d9973ce2fe
commit 457df33e03
1 changed files with 8 additions and 0 deletions
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8
fs/iomap/buffered-io.c
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@@ -302,6 +302,7 @@ iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
if (!ctx->bio || !is_contig || bio_full(ctx->bio, plen)) { if (!ctx->bio || !is_contig || bio_full(ctx->bio, plen)) {
gfp_t gfp = mapping_gfp_constraint(page->mapping, GFP_KERNEL); gfp_t gfp = mapping_gfp_constraint(page->mapping, GFP_KERNEL);
gfp_t orig_gfp = gfp;
int nr_vecs = (length + PAGE_SIZE - 1) >> PAGE_SHIFT; int nr_vecs = (length + PAGE_SIZE - 1) >> PAGE_SHIFT;
if (ctx->bio) if (ctx->bio)
@@ -310,6 +311,13 @@ iomap_readpage_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
if (ctx->is_readahead) /* same as readahead_gfp_mask */ if (ctx->is_readahead) /* same as readahead_gfp_mask */
gfp |= __GFP_NORETRY | __GFP_NOWARN; gfp |= __GFP_NORETRY | __GFP_NOWARN;
ctx->bio = bio_alloc(gfp, min(BIO_MAX_PAGES, nr_vecs)); ctx->bio = bio_alloc(gfp, min(BIO_MAX_PAGES, nr_vecs));
/*
* If the bio_alloc fails, try it again for a single page to
* avoid having to deal with partial page reads. This emulates
* what do_mpage_readpage does.
*/
if (!ctx->bio)
ctx->bio = bio_alloc(orig_gfp, 1);
ctx->bio->bi_opf = REQ_OP_READ; ctx->bio->bi_opf = REQ_OP_READ;
if (ctx->is_readahead) if (ctx->is_readahead)
ctx->bio->bi_opf |= REQ_RAHEAD; ctx->bio->bi_opf |= REQ_RAHEAD;