hfsplus: add per-superblock lock for volume header updates

Lock updates to the mutal fields in the volume header, and document the
locing in the hfsplus_sb_info structure.

Signed-off-by: Christoph Hellwig <hch@tuxera.com>

3 files changed, 50 insertions, 24 deletions

diff --git a/fs/hfsplus/dir.c b/fs/hfsplus/dir.c
index f8ae468f4ab6..1c81eedcab01 100644
--- a/fs/hfsplus/dir.c
+++ b/fs/hfsplus/dir.c
@@ -251,6 +251,7 @@ static int hfsplus_link(struct dentry *src_dentry, struct inode *dst_dir,
         if (HFSPLUS_IS_RSRC(inode))
                 return -EPERM;
 
+        mutex_lock(&sbi->vh_mutex);
         if (inode->i_ino == (u32)(unsigned long)src_dentry->d_fsdata) {
                 for (;;) {
                         get_random_bytes(&id, sizeof(cnid));
@@ -263,7 +264,7 @@ static int hfsplus_link(struct dentry *src_dentry, struct inode *dst_dir,
                         if (!res)
                                 break;
                         if (res != -EEXIST)
-                                return res;
+                                goto out;
                 }
                 HFSPLUS_I(inode)->dev = id;
                 cnid = sbi->next_cnid++;
@@ -271,13 +272,13 @@ static int hfsplus_link(struct dentry *src_dentry, struct inode *dst_dir,
                 res = hfsplus_create_cat(cnid, src_dir, &src_dentry->d_name, inode);
                 if (res)
                         /* panic? */
-                        return res;
+                        goto out;
                 sbi->file_count++;
         }
         cnid = sbi->next_cnid++;
         res = hfsplus_create_cat(cnid, dst_dir, &dst_dentry->d_name, inode);
         if (res)
-                return res;
+                goto out;
 
         inc_nlink(inode);
         hfsplus_instantiate(dst_dentry, inode, cnid);
@@ -286,8 +287,9 @@ static int hfsplus_link(struct dentry *src_dentry, struct inode *dst_dir,
         mark_inode_dirty(inode);
         sbi->file_count++;
         dst_dir->i_sb->s_dirt = 1;
-
-        return 0;
+out:
+        mutex_unlock(&sbi->vh_mutex);
+        return res;
 }
 
 static int hfsplus_unlink(struct inode *dir, struct dentry *dentry)
@@ -302,6 +304,7 @@ static int hfsplus_unlink(struct inode *dir, struct dentry *dentry)
         if (HFSPLUS_IS_RSRC(inode))
                 return -EPERM;
 
+        mutex_lock(&sbi->vh_mutex);
         cnid = (u32)(unsigned long)dentry->d_fsdata;
         if (inode->i_ino == cnid &&
             atomic_read(&HFSPLUS_I(inode)->opencnt)) {
@@ -312,11 +315,11 @@ static int hfsplus_unlink(struct inode *dir, struct dentry *dentry)
                                          sbi->hidden_dir, &str);
                 if (!res)
                         inode->i_flags |= S_DEAD;
-                return res;
+                goto out;
         }
         res = hfsplus_delete_cat(cnid, dir, &dentry->d_name);
         if (res)
-                return res;
+                goto out;
 
         if (inode->i_nlink > 0)
                 drop_nlink(inode);
@@ -339,37 +342,44 @@ static int hfsplus_unlink(struct inode *dir, struct dentry *dentry)
                 sbi->file_count--;
         inode->i_ctime = CURRENT_TIME_SEC;
         mark_inode_dirty(inode);
-
+out:
+        mutex_unlock(&sbi->vh_mutex);
         return res;
 }
 
 static int hfsplus_rmdir(struct inode *dir, struct dentry *dentry)
 {
-        struct inode *inode;
+        struct hfsplus_sb_info *sbi = HFSPLUS_SB(dir->i_sb);
+        struct inode *inode = dentry->d_inode;
         int res;
 
-        inode = dentry->d_inode;
         if (inode->i_size != 2)
                 return -ENOTEMPTY;
+
+        mutex_lock(&sbi->vh_mutex);
         res = hfsplus_delete_cat(inode->i_ino, dir, &dentry->d_name);
         if (res)
-                return res;
+                goto out;
         clear_nlink(inode);
         inode->i_ctime = CURRENT_TIME_SEC;
         hfsplus_delete_inode(inode);
         mark_inode_dirty(inode);
-        return 0;
+out:
+        mutex_unlock(&sbi->vh_mutex);
+        return res;
 }
 
 static int hfsplus_symlink(struct inode *dir, struct dentry *dentry,
                            const char *symname)
 {
+        struct hfsplus_sb_info *sbi = HFSPLUS_SB(dir->i_sb);
         struct inode *inode;
-        int res;
+        int res = -ENOSPC;
 
+        mutex_lock(&sbi->vh_mutex);
         inode = hfsplus_new_inode(dir->i_sb, S_IFLNK | S_IRWXUGO);
         if (!inode)
-                return -ENOSPC;
+                goto out;
 
         res = page_symlink(inode, symname, strlen(symname) + 1);
         if (res)
@@ -381,31 +391,35 @@ static int hfsplus_symlink(struct inode *dir, struct dentry *dentry,
 
         hfsplus_instantiate(dentry, inode, inode->i_ino);
         mark_inode_dirty(inode);
-        return 0;
+        goto out;
 
 out_err:
         inode->i_nlink = 0;
         hfsplus_delete_inode(inode);
         iput(inode);
+out:
+        mutex_unlock(&sbi->vh_mutex);
         return res;
 }
 
 static int hfsplus_mknod(struct inode *dir, struct dentry *dentry,
                          int mode, dev_t rdev)
 {
+        struct hfsplus_sb_info *sbi = HFSPLUS_SB(dir->i_sb);
         struct inode *inode;
-        int res;
+        int res = -ENOSPC;
 
+        mutex_lock(&sbi->vh_mutex);
         inode = hfsplus_new_inode(dir->i_sb, mode);
         if (!inode)
-                return -ENOSPC;
+                goto out;
 
         res = hfsplus_create_cat(inode->i_ino, dir, &dentry->d_name, inode);
         if (res) {
                 inode->i_nlink = 0;
                 hfsplus_delete_inode(inode);
                 iput(inode);
-                return res;
+                goto out;
         }
 
         if (S_ISBLK(mode) || S_ISCHR(mode) || S_ISFIFO(mode) || S_ISSOCK(mode))
@@ -413,7 +427,9 @@ static int hfsplus_mknod(struct inode *dir, struct dentry *dentry,
 
         hfsplus_instantiate(dentry, inode, inode->i_ino);
         mark_inode_dirty(inode);
-        return 0;
+out:
+        mutex_unlock(&sbi->vh_mutex);
+        return res;
 }
 
 static int hfsplus_create(struct inode *dir, struct dentry *dentry, int mode,
diff --git a/fs/hfsplus/hfsplus_fs.h b/fs/hfsplus/hfsplus_fs.h
index 0cd9ba00f968..08865ed70f00 100644
--- a/fs/hfsplus/hfsplus_fs.h
+++ b/fs/hfsplus/hfsplus_fs.h
@@ -116,23 +116,26 @@ struct hfsplus_sb_info {
         struct inode *hidden_dir;
         struct nls_table *nls;
 
-        /* synchronize block allocations */
-        struct mutex alloc_mutex;
-
         /* Runtime variables */
         u32 blockoffset;
         u32 sect_count;
         int fs_shift;
 
-        /* Stuff in host order from Vol Header */
+        /* immutable data from the volume header */
         u32 alloc_blksz;
         int alloc_blksz_shift;
         u32 total_blocks;
+        u32 data_clump_blocks, rsrc_clump_blocks;
+
+        /* mutable data from the volume header, protected by alloc_mutex */
         u32 free_blocks;
+        struct mutex alloc_mutex;
+
+        /* mutable data from the volume header, protected by vh_mutex */
         u32 next_cnid;
         u32 file_count;
         u32 folder_count;
-        u32 data_clump_blocks, rsrc_clump_blocks;
+        struct mutex vh_mutex;
 
         /* Config options */
         u32 creator;
diff --git a/fs/hfsplus/super.c b/fs/hfsplus/super.c
index 923f385b32ca..b766c170e4d8 100644
--- a/fs/hfsplus/super.c
+++ b/fs/hfsplus/super.c
@@ -160,6 +160,7 @@ int hfsplus_sync_fs(struct super_block *sb, int wait)
 
         dprint(DBG_SUPER, "hfsplus_write_super\n");
 
+        mutex_lock(&sbi->vh_mutex);
         mutex_lock(&sbi->alloc_mutex);
         sb->s_dirt = 0;
 
@@ -194,6 +195,7 @@ int hfsplus_sync_fs(struct super_block *sb, int wait)
                 sbi->flags &= ~HFSPLUS_SB_WRITEBACKUP;
         }
         mutex_unlock(&sbi->alloc_mutex);
+        mutex_unlock(&sbi->vh_mutex);
         return 0;
 }
 
@@ -319,6 +321,7 @@ static int hfsplus_fill_super(struct super_block *sb, void *data, int silent)
 
         sb->s_fs_info = sbi;
         mutex_init(&sbi->alloc_mutex);
+        mutex_init(&sbi->vh_mutex);
         hfsplus_fill_defaults(sbi);
         if (!hfsplus_parse_options(data, sbi)) {
                 printk(KERN_ERR "hfs: unable to parse mount options\n");
@@ -453,9 +456,13 @@ static int hfsplus_fill_super(struct super_block *sb, void *data, int silent)
 
         if (!sbi->hidden_dir) {
                 printk(KERN_DEBUG "hfs: create hidden dir...\n");
+
+                mutex_lock(&sbi->vh_mutex);
                 sbi->hidden_dir = hfsplus_new_inode(sb, S_IFDIR);
                 hfsplus_create_cat(sbi->hidden_dir->i_ino, sb->s_root->d_inode,
                                    &str, sbi->hidden_dir);
+                mutex_unlock(&sbi->vh_mutex);
+
                 mark_inode_dirty(sbi->hidden_dir);
         }
 out: