• Andreas Dilger's avatar
    ext4: xattr-in-inode support · e50e5129
    Andreas Dilger authored
    Large xattr support is implemented for EXT4_FEATURE_INCOMPAT_EA_INODE.
    
    If the size of an xattr value is larger than will fit in a single
    external block, then the xattr value will be saved into the body
    of an external xattr inode.
    
    The also helps support a larger number of xattr, since only the headers
    will be stored in the in-inode space or the single external block.
    
    The inode is referenced from the xattr header via "e_value_inum",
    which was formerly "e_value_block", but that field was never used.
    The e_value_size still contains the xattr size so that listing
    xattrs does not need to look up the inode if the data is not accessed.
    
    struct ext4_xattr_entry {
            __u8    e_name_len;     /* length of name */
            __u8    e_name_index;   /* attribute name index */
            __le16  e_value_offs;   /* offset in disk block of value */
            __le32  e_value_inum;   /* inode in which value is stored */
            __le32  e_value_size;   /* size of attribute value */
            __le32  e_hash;         /* hash value of name and value */
            char    e_name[0];      /* attribute name */
    };
    
    The xattr inode is marked with the EXT4_EA_INODE_FL flag and also
    holds a back-reference to the owning inode in its i_mtime field,
    allowing the ext4/e2fsck to verify the correct inode is accessed.
    
    [ Applied fix by Dan Carpenter to avoid freeing an ERR_PTR. ]
    
    Lustre-Jira: https://jira.hpdd.intel.com/browse/LU-80
    Lustre-bugzilla: https://bugzilla.lustre.org/show_bug.cgi?id=4424Signed-off-by: default avatarKalpak Shah <kalpak.shah@sun.com>
    Signed-off-by: default avatarJames Simmons <uja.ornl@gmail.com>
    Signed-off-by: default avatarAndreas Dilger <andreas.dilger@intel.com>
    Signed-off-by: default avatarTahsin Erdogan <tahsin@google.com>
    Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
    Signed-off-by: default avatarDan Carpenter <dan.carpenter@oracle.com>
    e50e5129
ext4.h 115 KB