Re: [PATCH] ext4: Don't set s_buddy_cache->i_ino to EXT4_BAD_INO
From: Andreas Dilger <hidden>
Date: 2011-08-17 15:31:11
On 2011-08-17, at 2:20 AM, Tao Ma [off-list ref] wrote:
In 85fe4025, Christoph removed get_next_ino() from new_inode() and do s_buddy_cache->i_ino = get_next_ino(); And then 48e6061b gives EXT4_BAD_INO to this inode. But actually s_buddy_cache is used directly and we never get it from an inode number. So it should be safe for us to not set i_ino at all and I guess that is the case Christoph described in his commit log of 85fe4025 "For a few more filesystems we can avoid assigning any inode number given that they aren't user visible".
I don't see that setting i_ino is harmful here (only done once per filesystem mount) and the comment clearly indicates that it is for precautionary reasons only. If this inode happens to appear in a crashdump for some reason, I'd prefer it has an inode number that can be identified easily rather than some random value left over from a previously allocated and freed inode, because inode_init_always() does not zero out i_ino.
quoted hunk ↗ jump to hunk
Cc: Yu Jian <redacted> Cc: Andreas Dilger <redacted> Cc: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by: Tao Ma <redacted> --- fs/ext4/mballoc.c | 5 ----- 1 files changed, 0 insertions(+), 5 deletions(-)diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index 17a5a57..982f783 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c@@ -2342,11 +2342,6 @@ static int ext4_mb_init_backend(struct super_block *sb) ext4_msg(sb, KERN_ERR, "can't get new inode"); goto err_freesgi; } - /* To avoid potentially colliding with an valid on-disk inode number, - * use EXT4_BAD_INO for the buddy cache inode number. This inode is - * not in the inode hash, so it should never be found by iget(), but - * this will avoid confusion if it ever shows up during debugging. */ - sbi->s_buddy_cache->i_ino = EXT4_BAD_INO; EXT4_I(sbi->s_buddy_cache)->i_disksize = 0; for (i = 0; i < ngroups; i++) { desc = ext4_get_group_desc(sb, i, NULL);-- 1.7.0.4 -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html