ext4: use journal inode to determine journal overhead

When a file system contains an internal journal that has not been
loaded, use the journal inode's i_size field to determine its
contribution to the file system's overhead.  (The journal's j_maxlen
field is normally used to determine its size, but it's unavailable when
the journal has not been loaded.)

Signed-off-by: Eric Whitney <enwlinux@gmail.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 056ca1bea2ac048919780a12e007edb57ed0ba43..6db81fbcbaa6cce558b6ef9f7e613e8284e898a6 100644 (file)
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3210,6 +3210,8 @@ int ext4_calculate_overhead(struct super_block *sb)
 {
        struct ext4_sb_info *sbi = EXT4_SB(sb);
        struct ext4_super_block *es = sbi->s_es;
+       struct inode *j_inode;
+       unsigned int j_blocks, j_inum = le32_to_cpu(es->s_journal_inum);
        ext4_group_t i, ngroups = ext4_get_groups_count(sb);
        ext4_fsblk_t overhead = 0;
        char *buf = (char *) get_zeroed_page(GFP_NOFS);
@@ -3240,10 +3242,23 @@ int ext4_calculate_overhead(struct super_block *sb)
                        memset(buf, 0, PAGE_SIZE);
                cond_resched();
        }
-       /* Add the internal journal blocks as well */
+
+       /*
+        * Add the internal journal blocks whether the journal has been
+        * loaded or not
+        */
        if (sbi->s_journal && !sbi->journal_bdev)
                overhead += EXT4_NUM_B2C(sbi, sbi->s_journal->j_maxlen);
-
+       else if (ext4_has_feature_journal(sb) && !sbi->s_journal) {
+               j_inode = ext4_get_journal_inode(sb, j_inum);
+               if (j_inode) {
+                       j_blocks = j_inode->i_size >> sb->s_blocksize_bits;
+                       overhead += EXT4_NUM_B2C(sbi, j_blocks);
+                       iput(j_inode);
+               } else {
+                       ext4_msg(sb, KERN_ERR, "can't get journal size");
+               }
+       }
        sbi->s_overhead = overhead;
        smp_wmb();
        free_page((unsigned long) buf);