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authorArtem Bityutskiy <artem.bityutskiy@linux.intel.com>2012-05-31 16:26:12 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-05-31 17:49:27 -0700
commit020ac5b6bef15785f9dde9de89d2734ff97da733 (patch)
tree18724448be398af715d45dea42966bf276d2febb /include/linux/msdos_fs.h
parent7bc1bac77a69011550ce0613f4a23712a002d7ad (diff)
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 <artem.bityutskiy@linux.intel.com> Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/msdos_fs.h')
-rw-r--r--include/linux/msdos_fs.h3
1 files changed, 2 insertions, 1 deletions
diff --git a/include/linux/msdos_fs.h b/include/linux/msdos_fs.h
index 34066e65fdeb..11cc2ac67e75 100644
--- a/include/linux/msdos_fs.h
+++ b/include/linux/msdos_fs.h
@@ -21,8 +21,9 @@
#define CT_LE_W(v) cpu_to_le16(v)
#define CT_LE_L(v) cpu_to_le32(v)
+#define MSDOS_ROOT_INO 1 /* The root inode number */
+#define MSDOS_FSINFO_INO 2 /* Used for managing the FSINFO block */
-#define MSDOS_ROOT_INO 1 /* == MINIX_ROOT_INO */
#define MSDOS_DIR_BITS 5 /* log2(sizeof(struct msdos_dir_entry)) */
/* directory limit */