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>

diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
index 3c9367b..ee985ca 100644 (file)
--- 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;
 }