fs/buffer.c: support buffer cache allocations with gfp modifiers
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>
diff --git a/fs/buffer.c b/fs/buffer.c
index 8f05111..9a6029e 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -993,7 +993,7 @@
*/
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 @@
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 @@
* 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 @@
}
/* 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 @@
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 @@
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 @@
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.