sys_swapon: separate bdev claim and inode lock

Move the code which claims the bdev (S_ISBLK) or locks the inode
(S_ISREG) to a separate function. Only code movement, no functional
changes.

Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.net>
Tested-by: Eric B Munson <emunson@mgebm.net>
Acked-by: Eric B Munson <emunson@mgebm.net>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 39 insertions, 25 deletions

diff --git a/mm/swapfile.c b/mm/swapfile.c
index 14590775212d..fc687b234eb5 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -1889,6 +1889,43 @@ static struct swap_info_struct *alloc_swap_info(void)
         return p;
 }
 
+static int claim_swapfile(struct swap_info_struct *p, struct inode *inode)
+{
+        int error;
+
+        if (S_ISBLK(inode->i_mode)) {
+                p->bdev = bdgrab(I_BDEV(inode));
+                error = blkdev_get(p->bdev,
+                                   FMODE_READ | FMODE_WRITE | FMODE_EXCL,
+                                   sys_swapon);
+                if (error < 0) {
+                        p->bdev = NULL;
+                        error = -EINVAL;
+                        goto bad_swap;
+                }
+                p->old_block_size = block_size(p->bdev);
+                error = set_blocksize(p->bdev, PAGE_SIZE);
+                if (error < 0)
+                        goto bad_swap;
+                p->flags |= SWP_BLKDEV;
+        } else if (S_ISREG(inode->i_mode)) {
+                p->bdev = inode->i_sb->s_bdev;
+                mutex_lock(&inode->i_mutex);
+                if (IS_SWAPFILE(inode)) {
+                        error = -EBUSY;
+                        goto bad_swap;
+                }
+        } else {
+                error = -EINVAL;
+                goto bad_swap;
+        }
+
+        return 0;
+
+bad_swap:
+        return error;
+}
+
 SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 {
         struct swap_info_struct *p;
@@ -1942,32 +1979,9 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
                 }
         }
 
-        if (S_ISBLK(inode->i_mode)) {
-                p->bdev = bdgrab(I_BDEV(inode));
-                error = blkdev_get(p->bdev,
-                                   FMODE_READ | FMODE_WRITE | FMODE_EXCL,
-                                   sys_swapon);
-                if (error < 0) {
-                        p->bdev = NULL;
-                        error = -EINVAL;
-                        goto bad_swap;
-                }
-                p->old_block_size = block_size(p->bdev);
-                error = set_blocksize(p->bdev, PAGE_SIZE);
-                if (error < 0)
-                        goto bad_swap;
-                p->flags |= SWP_BLKDEV;
-        } else if (S_ISREG(inode->i_mode)) {
-                p->bdev = inode->i_sb->s_bdev;
-                mutex_lock(&inode->i_mutex);
-                if (IS_SWAPFILE(inode)) {
-                        error = -EBUSY;
-                        goto bad_swap;
-                }
-        } else {
-                error = -EINVAL;
+        error = claim_swapfile(p, inode);
+        if (unlikely(error))
                 goto bad_swap;
-        }
 
         swapfilepages = i_size_read(inode) >> PAGE_SHIFT;