Commit 3ed65f04 authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle) Committed by Andrew Morton
Browse files

buffer: hoist GFP flags from grow_dev_page() to __getblk_gfp() 

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.

[willy@infradead.org: fix grow_dev_page() error handling]
  Link: https://lkml.kernel.org/r/ZRREEIwqiy5DijKB@casper.infradead.org
Link: https://lkml.kernel.org/r/20230914150011.843330-3-willy@infradead.org


Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Cc: Hui Zhu <teawater@antgroup.com>
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 2a418157

fs/buffer.c

+40 −21
Original line number Diff line number Diff line
@@ -1043,20 +1043,11 @@ 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) {
@@ -1069,7 +1060,10 @@ grow_dev_page(struct block_device *bdev, sector_t block, 
			goto failed;

	}



	bh = folio_alloc_buffers(folio, size, gfp_mask | __GFP_ACCOUNT);

	ret = -ENOMEM;

	bh = folio_alloc_buffers(folio, size, gfp | __GFP_ACCOUNT);

	if (!bh)

		goto failed;



	/*

	 * Link the folio to the buffers and initialise them.  Take the
@@ -1420,24 +1414,49 @@ __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);

include/linux/buffer_head.h

+2 −0
Original line number Diff line number Diff line
@@ -227,6 +227,8 @@ 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 *);