grow_dev_page() is only called by grow_buffers(). grow_buffers()
is only called by __getblk_slow() and __getblk_slow() is only called
from __getblk_gfp(), so it is safe to move the GFP flags setting
all the way up. With that done, add a new bdev_getblk() entry point
that leaves the GFP flags the way the caller specified them.
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
---
fs/buffer.c | 60 ++++++++++++++++++++++++-------------
include/linux/buffer_head.h | 2 ++
2 files changed, 41 insertions(+), 21 deletions(-)
diff --git a/fs/buffer.c b/fs/buffer.c
index 7326acc29541..122b7d16befb 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -1048,20 +1048,11 @@ grow_dev_page(struct block_device *bdev, sector_t block,
struct buffer_head *bh;
sector_t end_block;
int ret = 0;
- gfp_t gfp_mask;
-
- gfp_mask = mapping_gfp_constraint(inode->i_mapping, ~__GFP_FS) | gfp;
-
- /*
- * XXX: __getblk_slow() can not really deal with failure and
- * will endlessly loop on improvised global reclaim. Prefer
- * looping in the allocator rather than here, at least that
- * code knows what it's doing.
- */
- gfp_mask |= __GFP_NOFAIL;
folio = __filemap_get_folio(inode->i_mapping, index,
- FGP_LOCK | FGP_ACCESSED | FGP_CREAT, gfp_mask);
+ FGP_LOCK | FGP_ACCESSED | FGP_CREAT, gfp);
+ if (IS_ERR(folio))
+ return PTR_ERR(folio);
bh = folio_buffers(folio);
if (bh) {
@@ -1074,7 +1065,9 @@ grow_dev_page(struct block_device *bdev, sector_t block,
goto failed;
}
- bh = folio_alloc_buffers(folio, size, gfp_mask);
+ bh = folio_alloc_buffers(folio, size, gfp);
+ if (!bh)
+ goto failed;
/*
* Link the folio to the buffers and initialise them. Take the
@@ -1426,24 +1419,49 @@ __find_get_block(struct block_device *bdev, sector_t block, unsigned size)
}
EXPORT_SYMBOL(__find_get_block);
+/**
+ * bdev_getblk - Get a buffer_head in a block device's buffer cache.
+ * @bdev: The block device.
+ * @block: The block number.
+ * @size: The size of buffer_heads for this @bdev.
+ * @gfp: The memory allocation flags to use.
+ *
+ * In contrast to __getblk_gfp(), the @gfp flags must be all of the flags;
+ * they are not augmented with the mapping's GFP flags.
+ *
+ * Return: The buffer head, or NULL if memory could not be allocated.
+ */
+struct buffer_head *bdev_getblk(struct block_device *bdev, sector_t block,
+ unsigned size, gfp_t gfp)
+{
+ struct buffer_head *bh = __find_get_block(bdev, block, size);
+
+ might_alloc(gfp);
+ if (bh)
+ return bh;
+
+ return __getblk_slow(bdev, block, size, gfp);
+}
+EXPORT_SYMBOL(bdev_getblk);
+
/*
* __getblk_gfp() will locate (and, if necessary, create) the buffer_head
* which corresponds to the passed block_device, block and size. The
* returned buffer has its reference count incremented.
- *
- * __getblk_gfp() will lock up the machine if grow_dev_page's
- * try_to_free_buffers() attempt is failing. FIXME, perhaps?
*/
struct buffer_head *
__getblk_gfp(struct block_device *bdev, sector_t block,
unsigned size, gfp_t gfp)
{
- struct buffer_head *bh = __find_get_block(bdev, block, size);
+ gfp |= mapping_gfp_constraint(bdev->bd_inode->i_mapping, ~__GFP_FS);
- might_sleep();
- if (bh == NULL)
- bh = __getblk_slow(bdev, block, size, gfp);
- return bh;
+ /*
+ * Prefer looping in the allocator rather than here, at least that
+ * code knows what it's doing.
+ */
+ gfp |= __GFP_NOFAIL;
+
+ return bdev_getblk(bdev, block, size, gfp);
}
EXPORT_SYMBOL(__getblk_gfp);
diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h
index d17efb8b7976..01110db9213c 100644
--- a/include/linux/buffer_head.h
+++ b/include/linux/buffer_head.h
@@ -233,6 +233,8 @@ void __wait_on_buffer(struct buffer_head *);
wait_queue_head_t *bh_waitq_head(struct buffer_head *bh);
struct buffer_head *__find_get_block(struct block_device *bdev, sector_t block,
unsigned size);
+struct buffer_head *bdev_getblk(struct block_device *bdev, sector_t block,
+ unsigned size, gfp_t gfp);
struct buffer_head *__getblk_gfp(struct block_device *bdev, sector_t block,
unsigned size, gfp_t gfp);
void __brelse(struct buffer_head *);
--
2.40.1
