Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758926Ab2EDPXK (ORCPT ); Fri, 4 May 2012 11:23:10 -0400 Received: from mga14.intel.com ([143.182.124.37]:15107 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758821Ab2EDPWx (ORCPT ); Fri, 4 May 2012 11:22:53 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.71,315,1320652800"; d="scan'208";a="138930599" From: Artem Bityutskiy To: OGAWA Hirofumi , Andrew Morton Cc: Linux Kernel Maling List , Linux FS Maling List , Artem Bityutskiy Subject: [PATCH v3 4/4] fat: switch to fsinfo_inode Date: Fri, 4 May 2012 18:23:38 +0300 Message-Id: <1336145018-23319-5-git-send-email-dedekind1@gmail.com> X-Mailer: git-send-email 1.7.7.6 In-Reply-To: <1336145018-23319-1-git-send-email-dedekind1@gmail.com> References: <1336145018-23319-1-git-send-email-dedekind1@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4220 Lines: 134 From: Artem Bityutskiy Currently FAT file-system maps the VFS "superblock" abstraction to the FSINFO block. The FSINFO block contains non-essential data about the amount of free clusters and the next free cluster. FAT file-system can always find out this information by scanning the FAT table, but having it in the FSINFO block may speed things up sometimes. So FAT file-system relies on the VFS superblock write-out services to make sure the FSINFO block is written out to the media from time to time. The whole "superblock write-out" VFS infrastructure is served by the 'sync_supers()' kernel thread, which wakes up every 5 (by default) seconds and writes out all dirty superblock using the '->write_super()' call-back. But the problem with this thread is that it wastes power by waking up the system every 5 seconds no matter what. So we want to kill it completely and thus, we need to make file-systems to stop using the '->write_super' VFS service, and then remove it together with the kernel thread. This patch switches the FAT FSINFO block management from '->write_super()'/'->s_dirt' to 'fsinfo_inode'/'->write_inode'. Now, instead of setting the 's_dirt' flag, we just mark the special 'fsinfo_inode' inode as dirty and let VFS invoke the '->write_inode' call-back when needed, where we write-out the FSINFO block. This patch also makes sure we do not mark the 'fsinfo_inode' inode as dirty if we are not FAT32 (FAT16 and FAT12 do not have the FSINFO block) or if we are in R/O mode. As a bonus, we can also remove the '->sync_fs()' and '->write_super()' FAT call-back function because they become unneeded. Signed-off-by: Artem Bityutskiy --- fs/fat/fatent.c | 7 ++++++- fs/fat/inode.c | 42 ++++++++++++------------------------------ 2 files changed, 18 insertions(+), 31 deletions(-) diff --git a/fs/fat/fatent.c b/fs/fat/fatent.c index 8181548..31f08ab 100644 --- a/fs/fat/fatent.c +++ b/fs/fat/fatent.c @@ -310,7 +310,12 @@ void fat_ent_access_init(struct super_block *sb) static void mark_fsinfo_dirty(struct super_block *sb) { - sb->s_dirt = 1; + struct msdos_sb_info *sbi = MSDOS_SB(sb); + + if (sb->s_flags & MS_RDONLY || sbi->fat_bits != 32) + return; + + __mark_inode_dirty(sbi->fsinfo_inode, I_DIRTY_SYNC); } static inline int fat_ent_update_ptr(struct super_block *sb, diff --git a/fs/fat/inode.c b/fs/fat/inode.c index 91e9a8a..9a87ec4 100644 --- a/fs/fat/inode.c +++ b/fs/fat/inode.c @@ -459,37 +459,10 @@ static void fat_evict_inode(struct inode *inode) fat_detach(inode); } -static void fat_write_super(struct super_block *sb) -{ - lock_super(sb); - sb->s_dirt = 0; - - if (!(sb->s_flags & MS_RDONLY)) - fat_clusters_flush(sb); - unlock_super(sb); -} - -static int fat_sync_fs(struct super_block *sb, int wait) -{ - int err = 0; - - if (sb->s_dirt) { - lock_super(sb); - sb->s_dirt = 0; - err = fat_clusters_flush(sb); - unlock_super(sb); - } - - return err; -} - static void fat_put_super(struct super_block *sb) { struct msdos_sb_info *sbi = MSDOS_SB(sb); - if (sb->s_dirt) - fat_write_super(sb); - iput(sbi->fsinfo_inode); iput(sbi->fat_inode); @@ -662,7 +635,18 @@ retry: static int fat_write_inode(struct inode *inode, struct writeback_control *wbc) { - return __fat_write_inode(inode, wbc->sync_mode == WB_SYNC_ALL); + int err; + + if (inode->i_ino == MSDOS_FSINFO_INO) { + struct super_block *sb = inode->i_sb; + + lock_super(sb); + err = fat_clusters_flush(sb); + unlock_super(sb); + } else + err = __fat_write_inode(inode, wbc->sync_mode == WB_SYNC_ALL); + + return err; } int fat_sync_inode(struct inode *inode) @@ -679,8 +663,6 @@ static const struct super_operations fat_sops = { .write_inode = fat_write_inode, .evict_inode = fat_evict_inode, .put_super = fat_put_super, - .write_super = fat_write_super, - .sync_fs = fat_sync_fs, .statfs = fat_statfs, .remount_fs = fat_remount, -- 1.7.7.6 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/