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fs/buffer.c: support buffer cache allocations with gfp modifiers

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A buffer cache is allocated from movable area because it is referred
for a while and released soon.  But some filesystems are taking buffer
cache for a long time and it can disturb page migration.

New APIs are introduced to allocate buffer cache with user specific
flag.  *_gfp APIs are for user want to set page allocation flag for
page cache allocation.  And *_unmovable APIs are for the user wants to
allocate page cache from non-movable area.

Signed-off-by: Gioh Kim <gioh.kim@lge.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Gioh Kim 2014-09-04 22:04:42 -04:00 • committed by Theodore Ts'o
parent d26e2c4d72
commit 3b5e6454aa
2 changed files with 68 additions and 24 deletions
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45
fs/buffer.c
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@ -993,7 +993,7 @@ init_page_buffers(struct page *page, struct block_device *bdev,
*/
static int
grow_dev_page(struct block_device *bdev, sector_t block,
pgoff_t index, int size, int sizebits)
pgoff_t index, int size, int sizebits, gfp_t gfp)
{
struct inode *inode = bdev->bd_inode;
struct page *page;
@ -1002,8 +1002,8 @@ grow_dev_page(struct block_device *bdev, sector_t block,
int ret = 0; /* Will call free_more_memory() */
gfp_t gfp_mask;
gfp_mask = mapping_gfp_mask(inode->i_mapping) & ~__GFP_FS;
gfp_mask |= __GFP_MOVABLE;
gfp_mask = (mapping_gfp_mask(inode->i_mapping) & ~__GFP_FS) | gfp;
/*
* XXX: __getblk_slow() can not really deal with failure and
* will endlessly loop on improvised global reclaim. Prefer
@ -1058,7 +1058,7 @@ failed:
* that page was dirty, the buffers are set dirty also.
*/
static int
grow_buffers(struct block_device *bdev, sector_t block, int size)
grow_buffers(struct block_device *bdev, sector_t block, int size, gfp_t gfp)
{
pgoff_t index;
int sizebits;
@ -1085,11 +1085,12 @@ grow_buffers(struct block_device *bdev, sector_t block, int size)
}
/* Create a page with the proper size buffers.. */
return grow_dev_page(bdev, block, index, size, sizebits);
return grow_dev_page(bdev, block, index, size, sizebits, gfp);
}
static struct buffer_head *
__getblk_slow(struct block_device *bdev, sector_t block, int size)
struct buffer_head *
__getblk_slow(struct block_device *bdev, sector_t block,
unsigned size, gfp_t gfp)
{
/* Size must be multiple of hard sectorsize */
if (unlikely(size & (bdev_logical_block_size(bdev)-1) ||
@ -1111,13 +1112,14 @@ __getblk_slow(struct block_device *bdev, sector_t block, int size)
if (bh)
return bh;
ret = grow_buffers(bdev, block, size);
ret = grow_buffers(bdev, block, size, gfp);
if (ret < 0)
return NULL;
if (ret == 0)
free_more_memory();
}
}
EXPORT_SYMBOL(__getblk_slow);
/*
* The relationship between dirty buffers and dirty pages:
@ -1371,24 +1373,25 @@ __find_get_block(struct block_device *bdev, sector_t block, unsigned size)
EXPORT_SYMBOL(__find_get_block);
/*
* __getblk will locate (and, if necessary, create) the buffer_head
* __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() will lock up the machine if grow_dev_page's try_to_free_buffers()
* attempt is failing. FIXME, perhaps?
* __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(struct block_device *bdev, sector_t block, unsigned size)
__getblk_gfp(struct block_device *bdev, sector_t block,
unsigned size, gfp_t gfp)
{
struct buffer_head *bh = __find_get_block(bdev, block, size);
might_sleep();
if (bh == NULL)
bh = __getblk_slow(bdev, block, size);
bh = __getblk_slow(bdev, block, size, gfp);
return bh;
}
EXPORT_SYMBOL(__getblk);
EXPORT_SYMBOL(__getblk_gfp);
/*
* Do async read-ahead on a buffer..
@ -1404,24 +1407,28 @@ void __breadahead(struct block_device *bdev, sector_t block, unsigned size)
EXPORT_SYMBOL(__breadahead);
/**
* __bread() - reads a specified block and returns the bh
* __bread_gfp() - reads a specified block and returns the bh
* @bdev: the block_device to read from
* @block: number of block
* @size: size (in bytes) to read
*
* @gfp: page allocation flag
*
* Reads a specified block, and returns buffer head that contains it.
* The page cache can be allocated from non-movable area
* not to prevent page migration if you set gfp to zero.
* It returns NULL if the block was unreadable.
*/
struct buffer_head *
__bread(struct block_device *bdev, sector_t block, unsigned size)
__bread_gfp(struct block_device *bdev, sector_t block,
unsigned size, gfp_t gfp)
{
struct buffer_head *bh = __getblk(bdev, block, size);
struct buffer_head *bh = __getblk_gfp(bdev, block, size, gfp);
if (likely(bh) && !buffer_uptodate(bh))
bh = __bread_slow(bh);
return bh;
}
EXPORT_SYMBOL(__bread);
EXPORT_SYMBOL(__bread_gfp);
/*
* invalidate_bh_lrus() is called rarely - but not only at unmount.