From 3b5e6454aaf6b4439b19400d8365e2ec2d24e411 Mon Sep 17 00:00:00 2001 From: Gioh Kim Date: Thu, 4 Sep 2014 22:04:42 -0400 Subject: [PATCH] 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 Signed-off-by: Theodore Ts'o Reviewed-by: Jan Kara --- fs/buffer.c | 45 ++++++++++++++++++++--------------- include/linux/buffer_head.h | 47 +++++++++++++++++++++++++++++++++---- 2 files changed, 68 insertions(+), 24 deletions(-) diff --git a/fs/buffer.c b/fs/buffer.c index 8f05111bbb8b..9a6029e0dd71 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -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. diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h index 324329ceea1e..73b45225a7ca 100644 --- a/include/linux/buffer_head.h +++ b/include/linux/buffer_head.h @@ -175,12 +175,13 @@ 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 *__getblk(struct block_device *bdev, sector_t block, - unsigned size); +struct buffer_head *__getblk_gfp(struct block_device *bdev, sector_t block, + unsigned size, gfp_t gfp); void __brelse(struct buffer_head *); void __bforget(struct buffer_head *); void __breadahead(struct block_device *, sector_t block, unsigned int size); -struct buffer_head *__bread(struct block_device *, sector_t block, unsigned size); +struct buffer_head *__bread_gfp(struct block_device *, + sector_t block, unsigned size, gfp_t gfp); void invalidate_bh_lrus(void); struct buffer_head *alloc_buffer_head(gfp_t gfp_flags); void free_buffer_head(struct buffer_head * bh); @@ -295,7 +296,13 @@ static inline void bforget(struct buffer_head *bh) static inline struct buffer_head * sb_bread(struct super_block *sb, sector_t block) { - return __bread(sb->s_bdev, block, sb->s_blocksize); + return __bread_gfp(sb->s_bdev, block, sb->s_blocksize, __GFP_MOVABLE); +} + +static inline struct buffer_head * +sb_bread_unmovable(struct super_block *sb, sector_t block) +{ + return __bread_gfp(sb->s_bdev, block, sb->s_blocksize, 0); } static inline void @@ -307,7 +314,7 @@ sb_breadahead(struct super_block *sb, sector_t block) static inline struct buffer_head * sb_getblk(struct super_block *sb, sector_t block) { - return __getblk(sb->s_bdev, block, sb->s_blocksize); + return __getblk_gfp(sb->s_bdev, block, sb->s_blocksize, __GFP_MOVABLE); } static inline struct buffer_head * @@ -344,6 +351,36 @@ static inline void lock_buffer(struct buffer_head *bh) __lock_buffer(bh); } +static inline struct buffer_head *getblk_unmovable(struct block_device *bdev, + sector_t block, + unsigned size) +{ + return __getblk_gfp(bdev, block, size, 0); +} + +static inline struct buffer_head *__getblk(struct block_device *bdev, + sector_t block, + unsigned size) +{ + return __getblk_gfp(bdev, block, size, __GFP_MOVABLE); +} + +/** + * __bread() - 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 + * + * Reads a specified block, and returns buffer head that contains it. + * The page cache is allocated from movable area so that it can be migrated. + * It returns NULL if the block was unreadable. + */ +static inline struct buffer_head * +__bread(struct block_device *bdev, sector_t block, unsigned size) +{ + return __bread_gfp(bdev, block, size, __GFP_MOVABLE); +} + extern int __set_page_dirty_buffers(struct page *page); #else /* CONFIG_BLOCK */