From 389d1b083c767a360ec84b27a95da06244becec8 Mon Sep 17 00:00:00 2001 From: "Aneesh Kumar K.V" Date: Mon, 28 Jan 2008 23:58:26 -0500 Subject: [PATCH] Add buffer head related helper functions Add buffer head related helper function bh_uptodate_or_lock and bh_submit_read which can be used by file system Signed-off-by: Aneesh Kumar K.V --- fs/buffer.c | 44 +++++++++++++++++++++++++++++++++++++ include/linux/buffer_head.h | 2 ++ 2 files changed, 46 insertions(+) diff --git a/fs/buffer.c b/fs/buffer.c index 7249e014819e..456c9ab7705b 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -3213,6 +3213,50 @@ static int buffer_cpu_notify(struct notifier_block *self, return NOTIFY_OK; } +/** + * 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 zero on success and -EIO on error. + */ +int bh_submit_read(struct buffer_head *bh) +{ + BUG_ON(!buffer_locked(bh)); + + if (buffer_uptodate(bh)) { + unlock_buffer(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 --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h index da0d83fbadc0..e98801f06dcc 100644 --- a/include/linux/buffer_head.h +++ b/include/linux/buffer_head.h @@ -192,6 +192,8 @@ int sync_dirty_buffer(struct buffer_head *bh); 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; -- 2.20.1