[PATCH] md/bitmap: tidy up i_writecount handling in md/bitmap

md/bitmap modifies i_writecount of a bitmap file to make sure that no-one else
writes to it.  The reverting of the change is sometimes done twice, and there
is one error path where it is omitted.

This patch tidies that up.

Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 31 insertions, 26 deletions

diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index dfe5e12741ba..e40d3e4b8d27 100644
--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -625,7 +625,6 @@ static void drain_write_queues(struct bitmap *bitmap)
 static void bitmap_file_put(struct bitmap *bitmap)
 {
         struct file *file;
-        struct inode *inode;
         unsigned long flags;
 
         spin_lock_irqsave(&bitmap->lock, flags);
@@ -637,13 +636,8 @@ static void bitmap_file_put(struct bitmap *bitmap)
 
         bitmap_file_unmap(bitmap);
 
-        if (file) {
-                inode = file->f_mapping->host;
-                spin_lock(&inode->i_lock);
-                atomic_set(&inode->i_writecount, 1); /* allow writes again */
-                spin_unlock(&inode->i_lock);
+        if (file)
                 fput(file);
-        }
 }
 
 
diff --git a/drivers/md/md.c b/drivers/md/md.c
index ea6837d45fc8..7da9e2d023bb 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -2877,6 +2877,32 @@ out:
         return err;
 }
 
+/* similar to deny_write_access, but accounts for our holding a reference
+ * to the file ourselves */
+static int deny_bitmap_write_access(struct file * file)
+{
+        struct inode *inode = file->f_mapping->host;
+
+        spin_lock(&inode->i_lock);
+        if (atomic_read(&inode->i_writecount) > 1) {
+                spin_unlock(&inode->i_lock);
+                return -ETXTBSY;
+        }
+        atomic_set(&inode->i_writecount, -1);
+        spin_unlock(&inode->i_lock);
+
+        return 0;
+}
+
+static void restore_bitmap_write_access(struct file *file)
+{
+        struct inode *inode = file->f_mapping->host;
+
+        spin_lock(&inode->i_lock);
+        atomic_set(&inode->i_writecount, 1);
+        spin_unlock(&inode->i_lock);
+}
+
 static int do_md_stop(mddev_t * mddev, int ro)
 {
         int err = 0;
@@ -2940,7 +2966,7 @@ static int do_md_stop(mddev_t * mddev, int ro)
 
                 bitmap_destroy(mddev);
                 if (mddev->bitmap_file) {
-                        atomic_set(&mddev->bitmap_file->f_dentry->d_inode->i_writecount, 1);
+                        restore_bitmap_write_access(mddev->bitmap_file);
                         fput(mddev->bitmap_file);
                         mddev->bitmap_file = NULL;
                 }
@@ -3544,23 +3570,6 @@ abort_export:
         return err;
 }
 
-/* similar to deny_write_access, but accounts for our holding a reference
- * to the file ourselves */
-static int deny_bitmap_write_access(struct file * file)
-{
-        struct inode *inode = file->f_mapping->host;
-
-        spin_lock(&inode->i_lock);
-        if (atomic_read(&inode->i_writecount) > 1) {
-                spin_unlock(&inode->i_lock);
-                return -ETXTBSY;
-        }
-        atomic_set(&inode->i_writecount, -1);
-        spin_unlock(&inode->i_lock);
-
-        return 0;
-}
-
 static int set_bitmap_file(mddev_t *mddev, int fd)
 {
         int err;
@@ -3608,8 +3617,10 @@ static int set_bitmap_file(mddev_t *mddev, int fd)
                 mddev->pers->quiesce(mddev, 0);
         }
         if (fd < 0) {
-                if (mddev->bitmap_file)
+                if (mddev->bitmap_file) {
+                        restore_bitmap_write_access(mddev->bitmap_file);
                         fput(mddev->bitmap_file);
+                }
                 mddev->bitmap_file = NULL;
         }