From: "Aneesh Kumar K.V" Add buffer head related helper function bh_uptodate_or_lock() and bh_submit_read() which can be used by file systems. Signed-off-by: Aneesh Kumar K.V Cc: Signed-off-by: Andrew Morton --- fs/buffer.c | 41 ++++++++++++++++++++++++++++++++++ include/linux/buffer_head.h | 2 + 2 files changed, 43 insertions(+) diff -puN fs/buffer.c~add-buffer-head-related-helper-functions fs/buffer.c --- a/fs/buffer.c~add-buffer-head-related-helper-functions +++ a/fs/buffer.c @@ -3204,6 +3204,47 @@ init_buffer_head(struct kmem_cache *cach INIT_LIST_HEAD(&bh->b_assoc_buffers); } +/** + * bh_uptodate_or_lock: Test whether the buffer is uptodate + * @bh: struct buffer_head + * + * Return true if the buffer is up-to-date and false, + * with the buffer locked, if not. + */ +int bh_uptodate_or_lock(struct buffer_head *bh) +{ + if (!buffer_uptodate(bh)) { + lock_buffer(bh); + if (!buffer_uptodate(bh)) + return 0; + unlock_buffer(bh); + } + return 1; +} +EXPORT_SYMBOL(bh_uptodate_or_lock); +/** + * bh_submit_read: Submit a locked buffer for reading + * @bh: struct buffer_head + * + * Returns a negative error + */ +int bh_submit_read(struct buffer_head *bh) +{ + if (!buffer_locked(bh)) + lock_buffer(bh); + + if (buffer_uptodate(bh)) + return 0; + + get_bh(bh); + bh->b_end_io = end_buffer_read_sync; + submit_bh(READ, bh); + wait_on_buffer(bh); + if (buffer_uptodate(bh)) + return 0; + return -EIO; +} +EXPORT_SYMBOL(bh_submit_read); void __init buffer_init(void) { int nrpages; diff -puN include/linux/buffer_head.h~add-buffer-head-related-helper-functions include/linux/buffer_head.h --- a/include/linux/buffer_head.h~add-buffer-head-related-helper-functions +++ a/include/linux/buffer_head.h @@ -192,6 +192,8 @@ int sync_dirty_buffer(struct buffer_head int submit_bh(int, struct buffer_head *); void write_boundary_block(struct block_device *bdev, sector_t bblock, unsigned blocksize); +int bh_uptodate_or_lock(struct buffer_head *bh); +int bh_submit_read(struct buffer_head *bh); extern int buffer_heads_over_limit; _