ext4: remove while loop in mpage_map_and_submit_extent()

The while loop in mpage_map_and_submit_extent() is pointless; this
function is only called if mpd.map.m_len is non-zero, and at the end
of the while loop, mpage_map_and_submit_buffers sets mpd.map.m_len to
be zero on success.  (And on a failure, we return out of the while
loop anyway.)

Hence, the body of the while loop is guaranteed to execute once and
exactly once.  This also fixes a gcc warning complaining that err
might be left uninitialized.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: Jan Kara <jack@suse.cz>

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 06136b5a20275a97802ec25cff8cde672acb8a65..38777cbf61c904c30c2eb45a3f60a930abbeba84 100644 (file)
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2157,44 +2157,42 @@ static int mpage_map_and_submit_extent(handle_t *handle,
 
        mpd->io_submit.io_end->offset =
                                ((loff_t)map->m_lblk) << inode->i_blkbits;
-       while (map->m_len) {
-               err = mpage_map_one_extent(handle, mpd);
-               if (err < 0) {
-                       struct super_block *sb = inode->i_sb;
+       err = mpage_map_one_extent(handle, mpd);
+       if (err < 0) {
+               struct super_block *sb = inode->i_sb;
 
-                       /*
-                        * Need to commit transaction to free blocks. Let upper
-                        * layers sort it out.
-                        */
-                       if (err == -ENOSPC && ext4_count_free_clusters(sb))
-                               return -ENOSPC;
-
-                       if (!(EXT4_SB(sb)->s_mount_flags & EXT4_MF_FS_ABORTED)) {
-                               ext4_msg(sb, KERN_CRIT,
-                                        "Delayed block allocation failed for "
-                                        "inode %lu at logical offset %llu with"
-                                        " max blocks %u with error %d",
-                                        inode->i_ino,
-                                        (unsigned long long)map->m_lblk,
-                                        (unsigned)map->m_len, err);
-                               ext4_msg(sb, KERN_CRIT,
-                                        "This should not happen!! Data will "
-                                        "be lost\n");
-                               if (err == -ENOSPC)
-                                       ext4_print_free_blocks(inode);
-                       }
-                       /* invalidate all the pages */
-                       mpage_release_unused_pages(mpd, true);
-                       return err;
-               }
                /*
-                * Update buffer state, submit mapped pages, and get us new
-                * extent to map
+                * Need to commit transaction to free blocks. Let upper
+                * layers sort it out.
                 */
-               err = mpage_map_and_submit_buffers(mpd);
-               if (err < 0)
-                       return err;
+               if (err == -ENOSPC && ext4_count_free_clusters(sb))
+                       return -ENOSPC;
+
+               if (!(EXT4_SB(sb)->s_mount_flags & EXT4_MF_FS_ABORTED)) {
+                       ext4_msg(sb, KERN_CRIT,
+                                "Delayed block allocation failed for "
+                                "inode %lu at logical offset %llu with"
+                                " max blocks %u with error %d",
+                                inode->i_ino,
+                                (unsigned long long)map->m_lblk,
+                                (unsigned)map->m_len, err);
+                       ext4_msg(sb, KERN_CRIT,
+                                "This should not happen!! Data will "
+                                "be lost\n");
+                       if (err == -ENOSPC)
+                               ext4_print_free_blocks(inode);
+               }
+               /* invalidate all the pages */
+               mpage_release_unused_pages(mpd, true);
+               return err;
        }
+       /*
+        * Update buffer state, submit mapped pages, and get us new
+        * extent to map
+        */
+       err = mpage_map_and_submit_buffers(mpd);
+       if (err < 0)
+               return err;
 
        /* Update on-disk size after IO is submitted */
        disksize = ((loff_t)mpd->first_page) << PAGE_CACHE_SHIFT;