From: Theodore Ts'o Subject: [PATCH 1/3] add releasepage hooks to block devices which can be used by file systems Date: Sat, 3 Jan 2009 10:09:16 -0500 Message-ID: <1230995358-24013-2-git-send-email-tytso@mit.edu> References: <20081226050138.GU28946@ZenIV.linux.org.uk> <1230995358-24013-1-git-send-email-tytso@mit.edu> Cc: Ext4 Developers List , Theodore Ts'o , Toshiyuki Okajima , linux-fsdevel@vger.kernel.org To: Al Viro Return-path: Received: from thunk.org ([69.25.196.29]:37210 "EHLO thunker.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758702AbZACPJy (ORCPT ); Sat, 3 Jan 2009 10:09:54 -0500 In-Reply-To: <1230995358-24013-1-git-send-email-tytso@mit.edu> Sender: linux-ext4-owner@vger.kernel.org List-ID: Implement blkdev_releasepage() to release the buffer_heads and pages after we release private data belonging to a mounted filesystem. Cc: Toshiyuki Okajima Cc: linux-fsdevel@vger.kernel.org Signed-off-by: "Theodore Ts'o" --- fs/block_dev.c | 15 +++++++++++++++ fs/super.c | 2 ++ include/linux/fs.h | 2 ++ 3 files changed, 19 insertions(+), 0 deletions(-) diff --git a/fs/block_dev.c b/fs/block_dev.c index 99e0ae1..ef7d795 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -1219,6 +1219,20 @@ static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg) return blkdev_ioctl(bdev, mode, cmd, arg); } +/* + * Try to release a page associated with block device when the system + * is under memory pressure. + */ +static int blkdev_releasepage(struct page *page, gfp_t wait) +{ + struct super_block *super = BDEV_I(page->mapping->host)->bdev.bd_super; + + if (super && super->s_op->bdev_try_to_free_page) + return super->s_op->bdev_try_to_free_page(super, page, wait); + + return try_to_free_buffers(page); +} + static const struct address_space_operations def_blk_aops = { .readpage = blkdev_readpage, .writepage = blkdev_writepage, @@ -1226,6 +1240,7 @@ static const struct address_space_operations def_blk_aops = { .write_begin = blkdev_write_begin, .write_end = blkdev_write_end, .writepages = generic_writepages, + .releasepage = blkdev_releasepage, .direct_IO = blkdev_direct_IO, }; diff --git a/fs/super.c b/fs/super.c index 400a760..d7e200d 100644 --- a/fs/super.c +++ b/fs/super.c @@ -800,6 +800,7 @@ int get_sb_bdev(struct file_system_type *fs_type, } s->s_flags |= MS_ACTIVE; + bdev->bd_super = s; } return simple_set_mnt(mnt, s); @@ -819,6 +820,7 @@ void kill_block_super(struct super_block *sb) struct block_device *bdev = sb->s_bdev; fmode_t mode = sb->s_mode; + bdev->bd_super = 0; generic_shutdown_super(sb); sync_blockdev(bdev); close_bdev_exclusive(bdev, mode); diff --git a/include/linux/fs.h b/include/linux/fs.h index 4a853ef..911f812 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -553,6 +553,7 @@ struct address_space { struct block_device { dev_t bd_dev; /* not a kdev_t - it's a search key */ struct inode * bd_inode; /* will die */ + struct super_block * bd_super; int bd_openers; struct mutex bd_mutex; /* open/close mutex */ struct semaphore bd_mount_sem; @@ -1375,6 +1376,7 @@ struct super_operations { ssize_t (*quota_read)(struct super_block *, int, char *, size_t, loff_t); ssize_t (*quota_write)(struct super_block *, int, const char *, size_t, loff_t); #endif + int (*bdev_try_to_free_page)(struct super_block*, struct page*, gfp_t); }; /* -- 1.6.0.4.8.g36f27.dirty