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/cpfile.c b/fs/nilfs2/cpfile.c
index 300f1cd..b5a8cd6 100644
--- a/fs/nilfs2/cpfile.c
+++ b/fs/nilfs2/cpfile.c
@@ -384,9 +384,10 @@
}
static ssize_t nilfs_cpfile_do_get_cpinfo(struct inode *cpfile, __u64 *cnop,
- struct nilfs_cpinfo *ci, size_t nci)
+ void *buf, unsigned cisz, size_t nci)
{
struct nilfs_checkpoint *cp;
+ struct nilfs_cpinfo *ci = buf;
struct buffer_head *bh;
size_t cpsz = NILFS_MDT(cpfile)->mi_entry_size;
__u64 cur_cno = nilfs_mdt_cno(cpfile), cno = *cnop;
@@ -410,17 +411,22 @@
kaddr = kmap_atomic(bh->b_page, KM_USER0);
cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, bh, kaddr);
for (i = 0; i < ncps && n < nci; i++, cp = (void *)cp + cpsz) {
- if (!nilfs_checkpoint_invalid(cp))
- nilfs_cpfile_checkpoint_to_cpinfo(
- cpfile, cp, &ci[n++]);
+ if (!nilfs_checkpoint_invalid(cp)) {
+ nilfs_cpfile_checkpoint_to_cpinfo(cpfile, cp,
+ ci);
+ ci = (void *)ci + cisz;
+ n++;
+ }
}
kunmap_atomic(kaddr, KM_USER0);
brelse(bh);
}
ret = n;
- if (n > 0)
- *cnop = ci[n - 1].ci_cno + 1;
+ if (n > 0) {
+ ci = (void *)ci - cisz;
+ *cnop = ci->ci_cno + 1;
+ }
out:
up_read(&NILFS_MDT(cpfile)->mi_sem);
@@ -428,11 +434,12 @@
}
static ssize_t nilfs_cpfile_do_get_ssinfo(struct inode *cpfile, __u64 *cnop,
- struct nilfs_cpinfo *ci, size_t nci)
+ void *buf, unsigned cisz, size_t nci)
{
struct buffer_head *bh;
struct nilfs_cpfile_header *header;
struct nilfs_checkpoint *cp;
+ struct nilfs_cpinfo *ci = buf;
__u64 curr = *cnop, next;
unsigned long curr_blkoff, next_blkoff;
void *kaddr;
@@ -472,7 +479,9 @@
if (unlikely(nilfs_checkpoint_invalid(cp) ||
!nilfs_checkpoint_snapshot(cp)))
break;
- nilfs_cpfile_checkpoint_to_cpinfo(cpfile, cp, &ci[n++]);
+ nilfs_cpfile_checkpoint_to_cpinfo(cpfile, cp, ci);
+ ci = (void *)ci + cisz;
+ n++;
next = le64_to_cpu(cp->cp_snapshot_list.ssl_next);
if (next == 0)
break; /* reach end of the snapshot list */
@@ -511,13 +520,13 @@
*/
ssize_t nilfs_cpfile_get_cpinfo(struct inode *cpfile, __u64 *cnop, int mode,
- struct nilfs_cpinfo *ci, size_t nci)
+ void *buf, unsigned cisz, size_t nci)
{
switch (mode) {
case NILFS_CHECKPOINT:
- return nilfs_cpfile_do_get_cpinfo(cpfile, cnop, ci, nci);
+ return nilfs_cpfile_do_get_cpinfo(cpfile, cnop, buf, cisz, nci);
case NILFS_SNAPSHOT:
- return nilfs_cpfile_do_get_ssinfo(cpfile, cnop, ci, nci);
+ return nilfs_cpfile_do_get_ssinfo(cpfile, cnop, buf, cisz, nci);
default:
return -EINVAL;
}
@@ -535,7 +544,7 @@
ssize_t nci;
int ret;
- nci = nilfs_cpfile_do_get_cpinfo(cpfile, &tcno, &ci, 1);
+ nci = nilfs_cpfile_do_get_cpinfo(cpfile, &tcno, &ci, sizeof(ci), 1);
if (nci < 0)
return nci;
else if (nci == 0 || ci.ci_cno != cno)