From: "Aneesh Kumar K.V" Subject: Re: [PATCH 23/49] Add buffer head related helper functions Date: Thu, 24 Jan 2008 10:52:27 +0530 Message-ID: <20080124052227.GA7902@skywalker> References: <1200970948-17903-16-git-send-email-tytso@mit.edu> <1200970948-17903-17-git-send-email-tytso@mit.edu> <1200970948-17903-18-git-send-email-tytso@mit.edu> <1200970948-17903-19-git-send-email-tytso@mit.edu> <1200970948-17903-20-git-send-email-tytso@mit.edu> <1200970948-17903-21-git-send-email-tytso@mit.edu> <1200970948-17903-22-git-send-email-tytso@mit.edu> <1200970948-17903-23-git-send-email-tytso@mit.edu> <1200970948-17903-24-git-send-email-tytso@mit.edu> <20080123140648.788fbc49.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "Theodore Ts'o" , linux-kernel@vger.kernel.org, "linux-ext4@vger.kernel.org" To: Andrew Morton Return-path: Received: from e28smtp03.in.ibm.com ([59.145.155.3]:43649 "EHLO e28esmtp03.in.ibm.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750714AbYAXFWl (ORCPT ); Thu, 24 Jan 2008 00:22:41 -0500 Content-Disposition: inline In-Reply-To: <20080123140648.788fbc49.akpm@linux-foundation.org> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Wed, Jan 23, 2008 at 02:06:48PM -0800, Andrew Morton wrote: > > On Mon, 21 Jan 2008 22:02:02 -0500 "Theodore Ts'o" wrote: > > +} > > +EXPORT_SYMBOL(bh_uptodate_or_lock); > > +/** > > Missing newline. > > > + * 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; > > Here it can lock the buffer then return zero > > > + 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; > > Here it will unlock the buffer and return zero. > > This function is unusable when passed an unlocked buffer. > Updated patch below. commit 70d4ca32604e0935a8b9a49c5ac8b9c64c810693 Author: Aneesh Kumar K.V Date: Thu Jan 24 10:50:24 2008 +0530 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 diff --git a/fs/buffer.c b/fs/buffer.c index 7249e01..82aa2db 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -3213,6 +3213,53 @@ 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.If the input + * buffer is not locked returns -EINVAL + * + */ +int bh_submit_read(struct buffer_head *bh) +{ + if (!buffer_locked(bh)) + return -EINVAL; + + 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 da0d83f..e98801f 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;