• Tahsin Erdogan's avatar
    quota: add get_inode_usage callback to transfer multi-inode charges · 7a9ca53a
    Tahsin Erdogan authored
    Ext4 ea_inode feature allows storing xattr values in external inodes to
    be able to store values that are bigger than a block in size. Ext4 also
    has deduplication support for these type of inodes. With deduplication,
    the actual storage waste is eliminated but the users of such inodes are
    still charged full quota for the inodes as if there was no sharing
    happening in the background.
    
    This design requires ext4 to manually charge the users because the
    inodes are shared.
    
    An implication of this is that, if someone calls chown on a file that
    has such references we need to transfer the quota for the file and xattr
    inodes. Current dquot_transfer() function implicitly transfers one inode
    charge. With ea_inode feature, we would like to transfer multiple inode
    charges.
    
    Add get_inode_usage callback which can interrogate the total number of
    inodes that were charged for a given inode.
    
    [ Applied fix from Colin King to make sure the 'ret' variable is
      initialized on the successful return path.  Detected by
      CoverityScan, CID#1446616 ("Uninitialized scalar variable") --tytso]
    Signed-off-by: default avatarTahsin Erdogan <tahsin@google.com>
    Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
    Signed-off-by: default avatarColin Ian King <colin.king@canonical.com>
    Acked-by: default avatarJan Kara <jack@suse.cz>
    7a9ca53a
ioctl.c 26.9 KB