On 2011-08-17, at 2:20 AM, Tao Ma <tm@xxxxxx> 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.
> Cc: Yu Jian <yujian@xxxxxxxxxxxxx>
> Cc: Andreas Dilger <adilger@xxxxxxxxxxxxx>
> Cc: "Theodore Ts'o" <tytso@xxxxxxx>
> Signed-off-by: Tao Ma <boyu.mt@xxxxxxxxxx>
> ---
> 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@xxxxxxxxxxxxxxx
> More majordomo info at http://vger.kernel.org/majordomo-info.html
--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
