From: Artem Bityutskiy Date: Thu, 31 May 2012 23:26:12 +0000 (-0700) Subject: fat: introduce special inode for managing the FSINFO block X-Git-Tag: v3.5-rc1~21^2~59 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=020ac5b6bef15785f9dde9de89d2734ff97da733;p=pandora-kernel.git fat: introduce special inode for managing the FSINFO block This is patchset makes fatfs stop using the VFS '->write_super()' method for writing out the FSINFO block. The final goal is to get rid of the 'sync_supers()' kernel thread. This kernel thread wakes up every 5 seconds (by default) and calls '->write_super()' for all mounted file-systems. And the bad thing is that this is done even if all the superblocks are clean. Moreover, some file-systems do not even need this end they do not register the '->write_super()' method at all (e.g., btrfs). So 'sync_supers()' most often just generates useless wake-ups and wastes power. I am trying to make all file-systems independent of '->write_super()' and plan to remove 'sync_supers()' and '->write_super' completely once there are no more users. The '->write_supers()' method is mostly used by baroque file-systems like hfs, udf, etc. Modern file-systems like btrfs and xfs do not use it. This justifies removing this stuff from VFS completely and make every FS self-manage own superblock. Tested with xfstests. This patch: Preparation for further changes. It introduces a special inode ('fsinfo_inode') in FAT file-system which we'll later use for managing the FSINFO block. Note, this there is already one special inode ('fat_inode') which is used for managing the FAT tables. Introduce new 'MSDOS_FSINFO_INO' constant for this special inode. It is safe to do because FAT file-system does not store inode numbers on the media but generates them run-time. I've also cleaned up the comment to existing 'MSDOS_ROOT_INO' constant, while on it. Signed-off-by: Artem Bityutskiy Cc: OGAWA Hirofumi Cc: Al Viro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Reading git-diff-tree failed