Jorg Schummer <ext-jorg.2.schummer@xxxxxxxxx> writes:
> Standard FAT implementations cannot store any of the FAT root directory's
> timestamps. This commit adds the mount option 'rootts', which allows saving
> the FAT root directory timestamps as the timestamps of the FAT volume label
> directory entry. At least Mac OS X is known to support the same mechanism
> and interoperate with this commit.
>
> When mounting, the following values can be specified for the 'rootts' mount
> option:
>
> "rootts=ignore" ignores root directory timestamps. All timestamps are
> reset to 0 (1/1/1970). This has been the FAT behaviour
> prior to this patch.
>
> "rootts=preserve" tries to load and save the root directory's timestamps
> if a volume label entry exists. The mtime and atime are
> corrected based on root directory entries' ctime. This
> is the default.
>
> "rootts=save" tries to load and save the root directory's timestamps.
> The mtime and atime are corrected based on root
> directory entries' ctime. If the root directory was
> accessed but no volume label entry exists, the label
> "NO NAME" is created.
Um..., I'm still not sure though. rootts=save may not be needed for
this, because it seems a bit complex, and it can do on userland...
And some quick review of implement..
> + if (inode->i_ino == MSDOS_ROOT_INO) {
> + if (sbi->options.root_ts == FAT_ROOT_TS_IGNORE)
> + return 0;
> +
> + /* Write the timestamps of a FAT file system's root directory
> + * as the timestamps of the file system's label dir entry. */
> +
> + if (!MSDOS_I(inode)->i_pos) {
> + struct buffer_head *bh;
> + struct msdos_dir_entry *de;
> + loff_t i_pos;
> +
> + if (sbi->options.root_ts != FAT_ROOT_TS_SAVE)
> + /* No label present, but we should not
> + create one. Thus not complaining. */
> + return 0;
> +
> + printk(KERN_INFO "FAT: creating volume label "
> + "on %s to save root dir timestamps\n",
> + sb->s_id);
> +
> + err = fat_add_label_entry(inode, NULL);
> + if (err)
> + return err;
> + err = fat_get_label_entry(inode, &bh, &de, &i_pos);
> + if (err)
> + return err;
In this path, we don't have inode->i_mutex, so to look directry up is
wrong. I think adding label may move to userland.
I guess we should do all of preparation in fill_super().
> + remove_inode_hash(inode);
> + fat_attach(inode, i_pos);
> + insert_inode_hash(inode);
> + brelse(bh);
Root inode should never change the position, so this shouldn't be
needed.
Thanks.
--
OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>
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