• Eryu Guan's avatar
    ext4: use XATTR_CREATE in ext4_initxattrs() · 3f706c8c
    Eryu Guan authored
    I hit ENOSPC error when creating new file in a newly created ext4
    with ea_inode feature enabled, if selinux is enabled and ext4 is
    mounted without any selinux context. e.g.
      mkfs -t ext4 -O ea_inode -F /dev/sda5
      mount /dev/sda5 /mnt/ext4
      touch /mnt/ext4/testfile  # got ENOSPC here
    It turns out that we run out of journal credits in
    ext4_xattr_set_handle() when creating new selinux label for the
    newly created inode.
    This is because that in __ext4_new_inode() we use
    __ext4_xattr_set_credits() to calculate the reserved credits for new
    xattr, with the 'is_create' argument being true, which implies less
    credits in the ea_inode case. But we calculate the required credits
    in ext4_xattr_set_handle() with 'is_create' being false, which means
    we need more credits if ea_inode feature is enabled. So we don't
    have enough credits and error out with ENOSPC.
    Fix it by simply calling ext4_xattr_set_handle() with XATTR_CREATE
    flag in ext4_initxattrs(), so we end up with requiring less credits
    than reserved. The semantic of XATTR_CREATE is "Perform a pure
    create, which fails if the named attribute exists already." (from
    setxattr(2)), which is fine in this case, because we only call
    ext4_initxattrs() on newly created inode.
    Fixes: af65207c ("ext4: fix __ext4_new_inode() journal credits calculation")
    Cc: Tahsin Erdogan <tahsin@google.com>
    Signed-off-by: default avatarEryu Guan <guaneryu@gmail.com>
    Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
xattr_security.c 1.61 KB