hfsplus: add missing extent locking in hfsplus_write_inode

Most of the extent handling code already does proper SMP locking, but
hfsplus_write_inode was calling into hfsplus_ext_write_extent without
taking the extents_lock.  Fix this by splitting hfsplus_ext_write_extent
into an internal helper that expects the lock, and a public interface
that first acquires it.

Also add a few locking asserts and document the locking rules in
hfsplus_fs.h.

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

2 files changed, 34 insertions, 15 deletions

diff --git a/fs/hfsplus/extents.c b/fs/hfsplus/extents.c
index b1017eaa4fdc..0c9cb1820a52 100644
--- a/fs/hfsplus/extents.c
+++ b/fs/hfsplus/extents.c
@@ -88,6 +88,8 @@ static void __hfsplus_ext_write_extent(struct inode *inode, struct hfs_find_data
         struct hfsplus_inode_info *hip = HFSPLUS_I(inode);
         int res;
 
+        WARN_ON(!mutex_is_locked(&hip->extents_lock));
+
         hfsplus_ext_build_key(fd->search_key, inode->i_ino, hip->cached_start,
                               HFSPLUS_IS_RSRC(inode) ?
                                 HFSPLUS_TYPE_RSRC : HFSPLUS_TYPE_DATA);
@@ -108,7 +110,7 @@ static void __hfsplus_ext_write_extent(struct inode *inode, struct hfs_find_data
         }
 }
 
-void hfsplus_ext_write_extent(struct inode *inode)
+static void hfsplus_ext_write_extent_locked(struct inode *inode)
 {
         if (HFSPLUS_I(inode)->flags & HFSPLUS_FLG_EXT_DIRTY) {
                 struct hfs_find_data fd;
@@ -119,6 +121,13 @@ void hfsplus_ext_write_extent(struct inode *inode)
         }
 }
 
+void hfsplus_ext_write_extent(struct inode *inode)
+{
+        mutex_lock(&HFSPLUS_I(inode)->extents_lock);
+        hfsplus_ext_write_extent_locked(inode);
+        mutex_unlock(&HFSPLUS_I(inode)->extents_lock);
+}
+
 static inline int __hfsplus_ext_read_extent(struct hfs_find_data *fd,
                                             struct hfsplus_extent *extent,
                                             u32 cnid, u32 block, u8 type)
@@ -144,6 +153,8 @@ static inline int __hfsplus_ext_cache_extent(struct hfs_find_data *fd, struct in
         struct hfsplus_inode_info *hip = HFSPLUS_I(inode);
         int res;
 
+        WARN_ON(!mutex_is_locked(&hip->extents_lock));
+
         if (hip->flags & HFSPLUS_FLG_EXT_DIRTY)
                 __hfsplus_ext_write_extent(inode, fd);
 
@@ -433,7 +444,7 @@ out:
 
 insert_extent:
         dprint(DBG_EXTENT, "insert new extent\n");
-        hfsplus_ext_write_extent(inode);
+        hfsplus_ext_write_extent_locked(inode);
 
         memset(hip->cached_extents, 0, sizeof(hfsplus_extent_rec));
         hip->cached_extents[0].start_block = cpu_to_be32(start);
diff --git a/fs/hfsplus/hfsplus_fs.h b/fs/hfsplus/hfsplus_fs.h
index c521d44f0747..c007cc201279 100644
--- a/fs/hfsplus/hfsplus_fs.h
+++ b/fs/hfsplus/hfsplus_fs.h
@@ -158,28 +158,36 @@ struct hfsplus_sb_info {
 
 
 struct hfsplus_inode_info {
-        struct mutex extents_lock;
-        u32 clump_blocks, alloc_blocks;
-        sector_t fs_blocks;
-        /* Allocation extents from catalog record or volume header */
-        hfsplus_extent_rec first_extents;
-        u32 first_blocks;
-        hfsplus_extent_rec cached_extents;
-        u32 cached_start, cached_blocks;
         atomic_t opencnt;
 
-        struct inode *rsrc_inode;
+        /*
+         * Extent allocation information, protected by extents_lock.
+         */
+        u32 first_blocks;
+        u32 clump_blocks;
+        u32 alloc_blocks;
+        u32 cached_start;
+        u32 cached_blocks;
+        hfsplus_extent_rec first_extents;
+        hfsplus_extent_rec cached_extents;
         unsigned long flags;
+        struct mutex extents_lock;
 
+        /*
+         * Immutable data.
+         */
+        struct inode *rsrc_inode;
         __be32 create_date;
-        /* Device number in hfsplus_permissions in catalog */
         u32 dev;
-        /* BSD system and user file flags */
-        u8 rootflags;
-        u8 userflags;
 
+        /*
+         * Protected by i_mutex.
+         */
+        sector_t fs_blocks;
+        u8 rootflags, userflags;        /* BSD system and user file flags */
         struct list_head open_dir_list;
         loff_t phys_size;
+
         struct inode vfs_inode;
 };