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nilfs2: allow future expansion of metadata read out via get info ioctl

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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>
This commit is contained in:
Ryusuke Konishi
2009-05-12 03:58:47 +09:00
parent 258ef67e24
commit 003ff182fd
7 changed files with 54 additions and 39 deletions
Download Patch File Download Diff File Expand all files Collapse all files

33
fs/nilfs2/cpfile.c
View File

@@ -384,9 +384,10 @@ static void nilfs_cpfile_checkpoint_to_cpinfo(struct inode *cpfile,
}
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 @@ static ssize_t nilfs_cpfile_do_get_cpinfo(struct inode *cpfile, __u64 *cnop,
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_cpinfo(struct inode *cpfile, __u64 *cnop,
}
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 @@ static ssize_t nilfs_cpfile_do_get_ssinfo(struct inode *cpfile, __u64 *cnop,
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 @@ static ssize_t nilfs_cpfile_do_get_ssinfo(struct inode *cpfile, __u64 *cnop,
*/
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 @@ int nilfs_cpfile_delete_checkpoint(struct inode *cpfile, __u64 cno)
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)