ext4: fix online resizing when the # of block groups is constant

Commit 1c6bd7173d66b3 introduced a regression where an online resize
operation which did not change the number of block groups would fail,
i.e:

	mke2fs -t /dev/vdc 60000
	mount /dev/vdc
	resize2fs /dev/vdc 60001

This was due to a bug in the logic regarding when to try converting
the filesystem to use meta_bg.

Also fix up a number of other minor issues with the online resizing
code: (a) Fix a sparse warning; (b) only check to make sure the device
is large enough once, instead of multiple times through the resize
loop.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 14 insertions, 22 deletions

diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
index 3c9367b9bebd..ee985ca05100 100644
--- a/fs/ext4/resize.c
+++ b/fs/ext4/resize.c
@@ -1772,23 +1772,18 @@ static int ext4_convert_meta_bg(struct super_block *sb, struct inode *inode)
         handle_t *handle;
         struct ext4_sb_info *sbi = EXT4_SB(sb);
         struct ext4_super_block *es = sbi->s_es;
-        struct ext4_inode_info *ei = 0;
+        struct ext4_inode_info *ei = EXT4_I(inode);
         ext4_fsblk_t nr;
         int i, ret, err = 0;
         int credits = 1;
 
         ext4_msg(sb, KERN_INFO, "Converting file system to meta_bg");
-        if (EXT4_HAS_COMPAT_FEATURE(sb, EXT4_FEATURE_COMPAT_RESIZE_INODE)) {
+        if (inode) {
                 if (es->s_reserved_gdt_blocks) {
                         ext4_error(sb, "Unexpected non-zero "
                                    "s_reserved_gdt_blocks");
                         return -EPERM;
                 }
-                if (!inode) {
-                        ext4_error(sb, "Unexpected NULL resize_inode");
-                        return -EPERM;
-                }
-                ei = EXT4_I(inode);
 
                 /* Do a quick sanity check of the resize inode */
                 if (inode->i_blocks != 1 << (inode->i_blkbits - 9))
@@ -1873,12 +1868,19 @@ int ext4_resize_fs(struct super_block *sb, ext4_fsblk_t n_blocks_count)
         int err = 0, flexbg_size = 1 << sbi->s_log_groups_per_flex;
         int meta_bg;
 
+        /* See if the device is actually as big as what was requested */
+        bh = sb_bread(sb, n_blocks_count - 1);
+        if (!bh) {
+                ext4_warning(sb, "can't read last block, resize aborted");
+                return -ENOSPC;
+        }
+        brelse(bh);
+
 retry:
         o_blocks_count = ext4_blocks_count(es);
 
-        if (test_opt(sb, DEBUG))
-                ext4_msg(sb, KERN_DEBUG, "resizing filesystem from %llu "
-                       "to %llu blocks", o_blocks_count, n_blocks_count);
+        ext4_msg(sb, KERN_INFO, "resizing filesystem from %llu "
+                 "to %llu blocks", o_blocks_count, n_blocks_count);
 
         if (n_blocks_count < o_blocks_count) {
                 /* On-line shrinking not supported */
@@ -1922,7 +1924,7 @@ retry:
                 }
         }
 
-        if ((!resize_inode && !meta_bg) || n_group == o_group) {
+        if ((!resize_inode && !meta_bg) || n_blocks_count == o_blocks_count) {
                 err = ext4_convert_meta_bg(sb, resize_inode);
                 if (err)
                         goto out;
@@ -1937,14 +1939,6 @@ retry:
                 }
         }
 
-        /* See if the device is actually as big as what was requested */
-        bh = sb_bread(sb, n_blocks_count - 1);
-        if (!bh) {
-                ext4_warning(sb, "can't read last block, resize aborted");
-                return -ENOSPC;
-        }
-        brelse(bh);
-
         /* extend the last group */
         if (n_group == o_group)
                 add = n_blocks_count - o_blocks_count;
@@ -2005,8 +1999,6 @@ out:
                 free_flex_gd(flex_gd);
         if (resize_inode != NULL)
                 iput(resize_inode);
-        if (test_opt(sb, DEBUG))
-                ext4_msg(sb, KERN_DEBUG, "resized filesystem to %llu",
-                         n_blocks_count);
+        ext4_msg(sb, KERN_INFO, "resized filesystem to %llu", n_blocks_count);
         return err;
 }