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>

1 files changed, 21 insertions, 13 deletions

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;
 };