From 78491189ddb6d84d4a4abae992ed891a236d0263 Mon Sep 17 00:00:00 2001 From: Artem Bityutskiy Date: Thu, 31 May 2012 16:26:13 -0700 Subject: fat: switch to fsinfo_inode 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 Cc: OGAWA Hirofumi Cc: Al Viro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/fat/inode.c | 42 ++++++++++++------------------------------ 1 file changed, 12 insertions(+), 30 deletions(-) (limited to 'fs/fat/inode.c') diff --git a/fs/fat/inode.c b/fs/fat/inode.c index 84c602b4bb25..c2973ea5df9a 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, -- cgit v1.2.3