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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
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>
-rw-r--r--fs/fat/fat.h1
-rw-r--r--fs/fat/inode.c12
-rw-r--r--include/linux/msdos_fs.h3
3 files changed, 15 insertions, 1 deletions
diff --git a/fs/fat/fat.h b/fs/fat/fat.h
index 66994f316e18..951d12b61b58 100644
--- a/fs/fat/fat.h
+++ b/fs/fat/fat.h
@@ -82,6 +82,7 @@ struct msdos_sb_info {
int fatent_shift;
struct fatent_operations *fatent_ops;
struct inode *fat_inode;
+ struct inode *fsinfo_inode;
struct ratelimit_state ratelimit;
diff --git a/fs/fat/inode.c b/fs/fat/inode.c
index b3d290c1b513..84c602b4bb25 100644
--- a/fs/fat/inode.c
+++ b/fs/fat/inode.c
@@ -490,6 +490,7 @@ static void fat_put_super(struct super_block *sb)
if (sb->s_dirt)
fat_write_super(sb);
+ iput(sbi->fsinfo_inode);
iput(sbi->fat_inode);
unload_nls(sbi->nls_disk);
@@ -1244,6 +1245,7 @@ int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat,
void (*setup)(struct super_block *))
{
struct inode *root_inode = NULL, *fat_inode = NULL;
+ struct inode *fsinfo_inode = NULL;
struct buffer_head *bh;
struct fat_boot_sector *b;
struct msdos_sb_info *sbi;
@@ -1490,6 +1492,14 @@ int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat,
goto out_fail;
MSDOS_I(fat_inode)->i_pos = 0;
sbi->fat_inode = fat_inode;
+
+ fsinfo_inode = new_inode(sb);
+ if (!fsinfo_inode)
+ goto out_fail;
+ fsinfo_inode->i_ino = MSDOS_FSINFO_INO;
+ sbi->fsinfo_inode = fsinfo_inode;
+ insert_inode_hash(fsinfo_inode);
+
root_inode = new_inode(sb);
if (!root_inode)
goto out_fail;
@@ -1516,6 +1526,8 @@ out_invalid:
fat_msg(sb, KERN_INFO, "Can't find a valid FAT filesystem");
out_fail:
+ if (fsinfo_inode)
+ iput(fsinfo_inode);
if (fat_inode)
iput(fat_inode);
unload_nls(sbi->nls_io);
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 */