[PATCH] Replace obscure constructs in fs/block_dev.c

[Johannes Weiner]

Hi,

Andrew, I promised it [1], here goes. Patched against Linus' git-tree.

[1] http://lkml.org/lkml/2007/3/22/226

This patch replaces some obscure code-paths in fs/block_dev.c with more
readable versions.

Signed-off-by: Johannes Weiner <[EMAIL PROTECTED]>


diff --git a/fs/block_dev.c b/fs/block_dev.c
index ea1480a..1ffbb6d 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -660,26 +660,16 @@ void bd_forget(struct inode *inode)
 
 int bd_claim(struct block_device *bdev, void *holder)
 {
-       int res;
+       int res = 0;
        spin_lock(&bdev_lock);
 
-       /* first decide result */
-       if (bdev->bd_holder == holder)
-               res = 0;         /* already a holder */
-       else if (bdev->bd_holder != NULL)
-               res = -EBUSY;    /* held by someone else */
-       else if (bdev->bd_contains == bdev)
-               res = 0;         /* is a whole device which isn't held */
-
-       else if (bdev->bd_contains->bd_holder == bd_claim)
-               res = 0;         /* is a partition of a device that is being 
partitioned */
-       else if (bdev->bd_contains->bd_holder != NULL)
-               res = -EBUSY;    /* is a partition of a held device */
-       else
-               res = 0;         /* is a partition of an un-held device */
+       /* If already held by someone else or we have a
+        * partition of a held device, we do nothing. */
 
-       /* now impose change */
-       if (res==0) {
+       if (bdev->bd_holder || bdev->bd_contains->bd_holder)
+               res = -EBUSY;
+
+       if (!res) {
                /* note that for a whole device bd_holders
                 * will be incremented twice, and bd_holder will
                 * be set to bd_claim before being set to holder
@@ -874,7 +864,7 @@ static struct bd_holder *find_bd_holder(struct block_device 
*bdev,
  */
 static int add_bd_holder(struct block_device *bdev, struct bd_holder *bo)
 {
-       int ret;
+       int err;
 
        if (!bo)
                return -EINVAL;
@@ -882,15 +872,18 @@ static int add_bd_holder(struct block_device *bdev, 
struct bd_holder *bo)
        if (!bd_holder_grab_dirs(bdev, bo))
                return -EBUSY;
 
-       ret = add_symlink(bo->sdir, bo->sdev);
-       if (ret == 0) {
-               ret = add_symlink(bo->hdir, bo->hdev);
-               if (ret)
-                       del_symlink(bo->sdir, bo->sdev);
+       err = add_symlink(bo->sdir, bo->sdev);
+       if (err)
+               return err;
+
+       err = add_symlink(bo->hdir, bo->hdev);
+       if (err) {
+               del_symlink(bo->sdir, bo->sdev);
+               return err;
        }
-       if (ret == 0)
-               list_add_tail(&bo->list, &bdev->bd_holder_list);
-       return ret;
+               
+       list_add_tail(&bo->list, &bdev->bd_holder_list);
+       return 0;
 }
 
 /**
@@ -948,7 +941,7 @@ static struct bd_holder *del_bd_holder(struct block_device 
*bdev,
 static int bd_claim_by_kobject(struct block_device *bdev, void *holder,
                                struct kobject *kobj)
 {
-       int res;
+       int err;
        struct bd_holder *bo, *found;
 
        if (!kobj)
@@ -959,21 +952,25 @@ static int bd_claim_by_kobject(struct block_device *bdev, 
void *holder,
                return -ENOMEM;
 
        mutex_lock(&bdev->bd_mutex);
-       res = bd_claim(bdev, holder);
-       if (res == 0) {
-               found = find_bd_holder(bdev, bo);
-               if (found == NULL) {
-                       res = add_bd_holder(bdev, bo);
-                       if (res)
-                               bd_release(bdev);
-               }
-       }
 
-       if (res || found)
+       err = bd_claim(bdev, holder);
+       if (err)
+               goto out;
+
+       found = find_bd_holder(bdev, bo);
+       if (found)
+               goto out;
+
+       err = add_bd_holder(bdev, bo);
+       if (err)
+               bd_release(bdev);
+
+out:
+       if (err || found)
                free_bd_holder(bo);
-       mutex_unlock(&bdev->bd_mutex);
 
-       return res;
+       mutex_unlock(&bdev->bd_mutex);
+       return err;
 }
 
 /**