nilfs2: allow future expansion of metadata read out via get info ioctl
Nilfs has some ioctl commands to read out metadata from meta data
files:
- NILFS_IOCTL_GET_CPINFO for checkpoint file,
- NILFS_IOCTL_GET_SUINFO for segment usage file, and
- NILFS_IOCTL_GET_VINFO for Disk Address Transalation (DAT) file,
respectively.
Every routine on these metadata files is implemented so that it allows
future expansion of on-disk format. But, the above ioctl commands do
not support expansion even though nilfs_argv structure can handle
arbitrary size for data exchanged via ioctl.
This allows future expansion of the following structures which give
basic format of the "get information" ioctls:
- struct nilfs_cpinfo
- struct nilfs_suinfo
- struct nilfs_vinfo
So, this introduces forward compatility of such ioctl commands.
In this patch, a sanity check in nilfs_ioctl_get_info() function is
changed to accept larger data structure [1], and metadata read
routines are rewritten so that they become compatible for larger
structures; the routines will just ignore the remaining fields which
the current version of nilfs doesn't know.
[1] The ioctl function already has another upper limit (PAGE_SIZE
against a structure, which appears in nilfs_ioctl_wrap_copy
function), and this will not cause security problem.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
diff --git a/fs/nilfs2/sufile.c b/fs/nilfs2/sufile.c
index da12732..37994d4 100644
--- a/fs/nilfs2/sufile.c
+++ b/fs/nilfs2/sufile.c
@@ -587,7 +587,8 @@
* nilfs_sufile_get_suinfo -
* @sufile: inode of segment usage file
* @segnum: segment number to start looking
- * @si: array of suinfo
+ * @buf: array of suinfo
+ * @sisz: byte size of suinfo
* @nsi: size of suinfo array
*
* Description:
@@ -599,11 +600,12 @@
*
* %-ENOMEM - Insufficient amount of memory available.
*/
-ssize_t nilfs_sufile_get_suinfo(struct inode *sufile, __u64 segnum,
- struct nilfs_suinfo *si, size_t nsi)
+ssize_t nilfs_sufile_get_suinfo(struct inode *sufile, __u64 segnum, void *buf,
+ unsigned sisz, size_t nsi)
{
struct buffer_head *su_bh;
struct nilfs_segment_usage *su;
+ struct nilfs_suinfo *si = buf;
size_t susz = NILFS_MDT(sufile)->mi_entry_size;
struct the_nilfs *nilfs = NILFS_MDT(sufile)->mi_nilfs;
void *kaddr;
@@ -628,20 +630,22 @@
if (ret != -ENOENT)
goto out;
/* hole */
- memset(&si[i], 0, sizeof(struct nilfs_suinfo) * n);
+ memset(si, 0, sisz * n);
+ si = (void *)si + sisz * n;
continue;
}
kaddr = kmap_atomic(su_bh->b_page, KM_USER0);
su = nilfs_sufile_block_get_segment_usage(
sufile, segnum, su_bh, kaddr);
- for (j = 0; j < n; j++, su = (void *)su + susz) {
- si[i + j].sui_lastmod = le64_to_cpu(su->su_lastmod);
- si[i + j].sui_nblocks = le32_to_cpu(su->su_nblocks);
- si[i + j].sui_flags = le32_to_cpu(su->su_flags) &
+ for (j = 0; j < n;
+ j++, su = (void *)su + susz, si = (void *)si + sisz) {
+ si->sui_lastmod = le64_to_cpu(su->su_lastmod);
+ si->sui_nblocks = le32_to_cpu(su->su_nblocks);
+ si->sui_flags = le32_to_cpu(su->su_flags) &
~(1UL << NILFS_SEGMENT_USAGE_ACTIVE);
if (nilfs_segment_is_active(nilfs, segnum + j))
- si[i + j].sui_flags |=
+ si->sui_flags |=
(1UL << NILFS_SEGMENT_USAGE_ACTIVE);
}
kunmap_atomic(kaddr, KM_USER0);