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Date: Mon, 17 Jun 2013 09:58:07 -0400
From: Theodore Ts'o <tytso@....edu>
To: Ext4 Developers List <linux-ext4@...r.kernel.org>
Cc: Theodore Ts'o <tytso@....edu>, Jan Kara <jack@...e.cz>
Subject: [PATCH 1/2] 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@....edu>
Cc: Jan Kara <jack@...e.cz>
---
fs/ext4/inode.c | 66 ++++++++++++++++++++++++++++-----------------------------
1 file changed, 32 insertions(+), 34 deletions(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 2644679..0e61543 100644
--- 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;
--
1.7.12.rc0.22.gcdd159b
--
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