Push lock_super() into the ->remount_fs() of filesystems that care about it

Note that since we can't run into contention between remount_fs and write_super
(due to exclusion on s_umount), we have to care only about filesystems that
touch lock_super() on their own.  Out of those ext3, ext4, hpfs, sysv and ufs
do need it; fat doesn't since its ->remount_fs() only accesses assign-once
data (basically, it's "we have no atime on directories and only have atime on
files for vfat; force nodiratime and possibly noatime into *flags").

[folded a build fix from hch]

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

6 files changed, 21 insertions, 3 deletions

diff --git a/fs/ext3/super.c b/fs/ext3/super.c
index 546b8d732bf2..e213a2613a56 100644
--- a/fs/ext3/super.c
+++ b/fs/ext3/super.c
@@ -2491,6 +2491,7 @@ static int ext3_remount (struct super_block * sb, int * flags, char * data)
 #endif
 
         /* Store the original options */
+        lock_super(sb);
         old_sb_flags = sb->s_flags;
         old_opts.s_mount_opt = sbi->s_mount_opt;
         old_opts.s_resuid = sbi->s_resuid;
@@ -2598,6 +2599,7 @@ static int ext3_remount (struct super_block * sb, int * flags, char * data)
                     old_opts.s_qf_names[i] != sbi->s_qf_names[i])
                         kfree(old_opts.s_qf_names[i]);
 #endif
+        unlock_super(sb);
         return 0;
 restore_opts:
         sb->s_flags = old_sb_flags;
@@ -2614,6 +2616,7 @@ restore_opts:
                 sbi->s_qf_names[i] = old_opts.s_qf_names[i];
         }
 #endif
+        unlock_super(sb);
         return err;
 }
 
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 1d4180b86772..a9c683425929 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3421,6 +3421,7 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data)
 #endif
 
         /* Store the original options */
+        lock_super(sb);
         old_sb_flags = sb->s_flags;
         old_opts.s_mount_opt = sbi->s_mount_opt;
         old_opts.s_resuid = sbi->s_resuid;
@@ -3554,6 +3555,7 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data)
                     old_opts.s_qf_names[i] != sbi->s_qf_names[i])
                         kfree(old_opts.s_qf_names[i]);
 #endif
+        unlock_super(sb);
         return 0;
 
 restore_opts:
@@ -3573,6 +3575,7 @@ restore_opts:
                 sbi->s_qf_names[i] = old_opts.s_qf_names[i];
         }
 #endif
+        unlock_super(sb);
         return err;
 }
 
diff --git a/fs/hpfs/super.c b/fs/hpfs/super.c
index 437a32e9deac..f68193cf0811 100644
--- a/fs/hpfs/super.c
+++ b/fs/hpfs/super.c
@@ -398,6 +398,7 @@ static int hpfs_remount_fs(struct super_block *s, int *flags, char *data)
         
         *flags |= MS_NOATIME;
         
+        lock_super(s);
         uid = sbi->sb_uid; gid = sbi->sb_gid;
         umask = 0777 & ~sbi->sb_mode;
         lowercase = sbi->sb_lowercase; conv = sbi->sb_conv;
@@ -430,9 +431,11 @@ static int hpfs_remount_fs(struct super_block *s, int *flags, char *data)
 
         replace_mount_options(s, new_opts);
 
+        unlock_super(s);
         return 0;
 
 out_err:
+        unlock_super(s);
         kfree(new_opts);
         return -EINVAL;
 }
diff --git a/fs/super.c b/fs/super.c
index bdd7158b785e..2a49fed77453 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -556,9 +556,7 @@ int do_remount_sb(struct super_block *sb, int flags, void *data, int force)
         remount_rw = !(flags & MS_RDONLY) && (sb->s_flags & MS_RDONLY);
 
         if (sb->s_op->remount_fs) {
-                lock_super(sb);
                 retval = sb->s_op->remount_fs(sb, &flags, data);
-                unlock_super(sb);
                 if (retval)
                         return retval;
         }
diff --git a/fs/sysv/inode.c b/fs/sysv/inode.c
index a8189864c241..e0a39f1fb88e 100644
--- a/fs/sysv/inode.c
+++ b/fs/sysv/inode.c
@@ -61,10 +61,12 @@ clean:
 static int sysv_remount(struct super_block *sb, int *flags, char *data)
 {
         struct sysv_sb_info *sbi = SYSV_SB(sb);
+        lock_super(sb);
         if (sbi->s_forced_ro)
                 *flags |= MS_RDONLY;
         if (!(*flags & MS_RDONLY))
                 sb->s_dirt = 1;
+        unlock_super(sb);
         return 0;
 }
 
diff --git a/fs/ufs/super.c b/fs/ufs/super.c
index 2b4d2b6234df..a5ecabfdc976 100644
--- a/fs/ufs/super.c
+++ b/fs/ufs/super.c
@@ -1181,6 +1181,7 @@ static int ufs_remount (struct super_block *sb, int *mount_flags, char *data)
         unsigned new_mount_opt, ufstype;
         unsigned flags;
         
+        lock_super(sb);
         uspi = UFS_SB(sb)->s_uspi;
         flags = UFS_SB(sb)->s_flags;
         usb1 = ubh_get_usb_first(uspi);
@@ -1193,17 +1194,21 @@ static int ufs_remount (struct super_block *sb, int *mount_flags, char *data)
         ufstype = UFS_SB(sb)->s_mount_opt & UFS_MOUNT_UFSTYPE;
         new_mount_opt = 0;
         ufs_set_opt (new_mount_opt, ONERROR_LOCK);
-        if (!ufs_parse_options (data, &new_mount_opt))
+        if (!ufs_parse_options (data, &new_mount_opt)) {
+                unlock_super(sb);
                 return -EINVAL;
+        }
         if (!(new_mount_opt & UFS_MOUNT_UFSTYPE)) {
                 new_mount_opt |= ufstype;
         } else if ((new_mount_opt & UFS_MOUNT_UFSTYPE) != ufstype) {
                 printk("ufstype can't be changed during remount\n");
+                unlock_super(sb);
                 return -EINVAL;
         }
 
         if ((*mount_flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY)) {
                 UFS_SB(sb)->s_mount_opt = new_mount_opt;
+                unlock_super(sb);
                 return 0;
         }
         
@@ -1228,6 +1233,7 @@ static int ufs_remount (struct super_block *sb, int *mount_flags, char *data)
 #ifndef CONFIG_UFS_FS_WRITE
                 printk("ufs was compiled with read-only support, "
                 "can't be mounted as read-write\n");
+                unlock_super(sb);
                 return -EINVAL;
 #else
                 if (ufstype != UFS_MOUNT_UFSTYPE_SUN && 
@@ -1236,16 +1242,19 @@ static int ufs_remount (struct super_block *sb, int *mount_flags, char *data)
                     ufstype != UFS_MOUNT_UFSTYPE_SUNx86 &&
                     ufstype != UFS_MOUNT_UFSTYPE_UFS2) {
                         printk("this ufstype is read-only supported\n");
+                        unlock_super(sb);
                         return -EINVAL;
                 }
                 if (!ufs_read_cylinder_structures(sb)) {
                         printk("failed during remounting\n");
+                        unlock_super(sb);
                         return -EPERM;
                 }
                 sb->s_flags &= ~MS_RDONLY;
 #endif
         }
         UFS_SB(sb)->s_mount_opt = new_mount_opt;
+        unlock_super(sb);
         return 0;
 }