From 454e2398be9b9fa30433fccc548db34d19aa9958 Mon Sep 17 00:00:00 2001 From: David Howells Date: Fri, 23 Jun 2006 02:02:57 -0700 Subject: [PATCH] VFS: Permit filesystem to override root dentry on mount Extend the get_sb() filesystem operation to take an extra argument that permits the VFS to pass in the target vfsmount that defines the mountpoint. The filesystem is then required to manually set the superblock and root dentry pointers. For most filesystems, this should be done with simple_set_mnt() which will set the superblock pointer and then set the root dentry to the superblock's s_root (as per the old default behaviour). The get_sb() op now returns an integer as there's now no need to return the superblock pointer. This patch permits a superblock to be implicitly shared amongst several mount points, such as can be done with NFS to avoid potential inode aliasing. In such a case, simple_set_mnt() would not be called, and instead the mnt_root and mnt_sb would be set directly. The patch also makes the following changes: (*) the get_sb_*() convenience functions in the core kernel now take a vfsmount pointer argument and return an integer, so most filesystems have to change very little. (*) If one of the convenience function is not used, then get_sb() should normally call simple_set_mnt() to instantiate the vfsmount. This will always return 0, and so can be tail-called from get_sb(). (*) generic_shutdown_super() now calls shrink_dcache_sb() to clean up the dcache upon superblock destruction rather than shrink_dcache_anon(). This is required because the superblock may now have multiple trees that aren't actually bound to s_root, but that still need to be cleaned up. The currently called functions assume that the whole tree is rooted at s_root, and that anonymous dentries are not the roots of trees which results in dentries being left unculled. However, with the way NFS superblock sharing are currently set to be implemented, these assumptions are violated: the root of the filesystem is simply a dummy dentry and inode (the real inode for '/' may well be inaccessible), and all the vfsmounts are rooted on anonymous[*] dentries with child trees. [*] Anonymous until discovered from another tree. (*) The documentation has been adjusted, including the additional bit of changing ext2_* into foo_* in the documentation. [akpm@osdl.org: convert ipath_fs, do other stuff] Signed-off-by: David Howells Acked-by: Al Viro Cc: Nathan Scott Cc: Roland Dreier Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/ext2/super.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'fs/ext2/super.c') diff --git a/fs/ext2/super.c b/fs/ext2/super.c index 7e30bae174e..a4dfffac596 100644 --- a/fs/ext2/super.c +++ b/fs/ext2/super.c @@ -1087,10 +1087,10 @@ static int ext2_statfs (struct super_block * sb, struct kstatfs * buf) return 0; } -static struct super_block *ext2_get_sb(struct file_system_type *fs_type, - int flags, const char *dev_name, void *data) +static int ext2_get_sb(struct file_system_type *fs_type, + int flags, const char *dev_name, void *data, struct vfsmount *mnt) { - return get_sb_bdev(fs_type, flags, dev_name, data, ext2_fill_super); + return get_sb_bdev(fs_type, flags, dev_name, data, ext2_fill_super, mnt); } #ifdef CONFIG_QUOTA -- cgit From 726c334223180e3c0197cc980a432681370d4baf Mon Sep 17 00:00:00 2001 From: David Howells Date: Fri, 23 Jun 2006 02:02:58 -0700 Subject: [PATCH] VFS: Permit filesystem to perform statfs with a known root dentry Give the statfs superblock operation a dentry pointer rather than a superblock pointer. This complements the get_sb() patch. That reduced the significance of sb->s_root, allowing NFS to place a fake root there. However, NFS does require a dentry to use as a target for the statfs operation. This permits the root in the vfsmount to be used instead. linux/mount.h has been added where necessary to make allyesconfig build successfully. Interest has also been expressed for use with the FUSE and XFS filesystems. Signed-off-by: David Howells Acked-by: Al Viro Cc: Nathan Scott Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/ext2/super.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'fs/ext2/super.c') diff --git a/fs/ext2/super.c b/fs/ext2/super.c index a4dfffac596..a6c4d6e0232 100644 --- a/fs/ext2/super.c +++ b/fs/ext2/super.c @@ -39,7 +39,7 @@ static void ext2_sync_super(struct super_block *sb, struct ext2_super_block *es); static int ext2_remount (struct super_block * sb, int * flags, char * data); -static int ext2_statfs (struct super_block * sb, struct kstatfs * buf); +static int ext2_statfs (struct dentry * dentry, struct kstatfs * buf); void ext2_error (struct super_block * sb, const char * function, const char * fmt, ...) @@ -1038,8 +1038,9 @@ restore_opts: return err; } -static int ext2_statfs (struct super_block * sb, struct kstatfs * buf) +static int ext2_statfs (struct dentry * dentry, struct kstatfs * buf) { + struct super_block *sb = dentry->d_sb; struct ext2_sb_info *sbi = EXT2_SB(sb); unsigned long overhead; int i; -- cgit From 0216bfcffe424a5473daa4da47440881b36c1f41 Mon Sep 17 00:00:00 2001 From: Mingming Cao Date: Fri, 23 Jun 2006 02:05:41 -0700 Subject: [PATCH] percpu counter data type changes to suppport more than 2**31 ext3 free blocks counter The percpu counter data type are changed in this set of patches to support more users like ext3 who need more than 32 bit to store the free blocks total in the filesystem. - Generic perpcu counters data type changes. The size of the global counter and local counter were explictly specified using s64 and s32. The global counter is changed from long to s64, while the local counter is changed from long to s32, so we could avoid doing 64 bit update in most cases. - Users of the percpu counters are updated to make use of the new percpu_counter_init() routine now taking an additional parameter to allow users to pass the initial value of the global counter. Signed-off-by: Mingming Cao Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/ext2/super.c | 25 +++++++++++++------------ 1 file changed, 13 insertions(+), 12 deletions(-) (limited to 'fs/ext2/super.c') diff --git a/fs/ext2/super.c b/fs/ext2/super.c index a6c4d6e0232..ee4ba759581 100644 --- a/fs/ext2/super.c +++ b/fs/ext2/super.c @@ -834,9 +834,6 @@ static int ext2_fill_super(struct super_block *sb, void *data, int silent) printk ("EXT2-fs: not enough memory\n"); goto failed_mount; } - percpu_counter_init(&sbi->s_freeblocks_counter); - percpu_counter_init(&sbi->s_freeinodes_counter); - percpu_counter_init(&sbi->s_dirs_counter); bgl_lock_init(&sbi->s_blockgroup_lock); sbi->s_debts = kmalloc(sbi->s_groups_count * sizeof(*sbi->s_debts), GFP_KERNEL); @@ -863,6 +860,13 @@ static int ext2_fill_super(struct super_block *sb, void *data, int silent) sbi->s_gdb_count = db_count; get_random_bytes(&sbi->s_next_generation, sizeof(u32)); spin_lock_init(&sbi->s_next_gen_lock); + + percpu_counter_init(&sbi->s_freeblocks_counter, + ext2_count_free_blocks(sb)); + percpu_counter_init(&sbi->s_freeinodes_counter, + ext2_count_free_inodes(sb)); + percpu_counter_init(&sbi->s_dirs_counter, + ext2_count_dirs(sb)); /* * set up enough so that it can read an inode */ @@ -874,24 +878,18 @@ static int ext2_fill_super(struct super_block *sb, void *data, int silent) if (!sb->s_root) { iput(root); printk(KERN_ERR "EXT2-fs: get root inode failed\n"); - goto failed_mount2; + goto failed_mount3; } if (!S_ISDIR(root->i_mode) || !root->i_blocks || !root->i_size) { dput(sb->s_root); sb->s_root = NULL; printk(KERN_ERR "EXT2-fs: corrupt root inode, run e2fsck\n"); - goto failed_mount2; + goto failed_mount3; } if (EXT2_HAS_COMPAT_FEATURE(sb, EXT3_FEATURE_COMPAT_HAS_JOURNAL)) ext2_warning(sb, __FUNCTION__, "mounting ext3 filesystem as ext2"); ext2_setup_super (sb, es, sb->s_flags & MS_RDONLY); - percpu_counter_mod(&sbi->s_freeblocks_counter, - ext2_count_free_blocks(sb)); - percpu_counter_mod(&sbi->s_freeinodes_counter, - ext2_count_free_inodes(sb)); - percpu_counter_mod(&sbi->s_dirs_counter, - ext2_count_dirs(sb)); return 0; cantfind_ext2: @@ -899,7 +897,10 @@ cantfind_ext2: printk("VFS: Can't find an ext2 filesystem on dev %s.\n", sb->s_id); goto failed_mount; - +failed_mount3: + percpu_counter_destroy(&sbi->s_freeblocks_counter); + percpu_counter_destroy(&sbi->s_freeinodes_counter); + percpu_counter_destroy(&sbi->s_dirs_counter); failed_mount2: for (i = 0; i < db_count; i++) brelse(sbi->s_group_desc[i]); -- cgit