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/dat.c b/fs/nilfs2/dat.c
index 1827f62..0b2710e 100644
--- a/fs/nilfs2/dat.c
+++ b/fs/nilfs2/dat.c
@@ -376,36 +376,37 @@
return ret;
}
-ssize_t nilfs_dat_get_vinfo(struct inode *dat, struct nilfs_vinfo *vinfo,
+ssize_t nilfs_dat_get_vinfo(struct inode *dat, void *buf, unsigned visz,
size_t nvi)
{
struct buffer_head *entry_bh;
struct nilfs_dat_entry *entry;
+ struct nilfs_vinfo *vinfo = buf;
__u64 first, last;
void *kaddr;
unsigned long entries_per_block = NILFS_MDT(dat)->mi_entries_per_block;
int i, j, n, ret;
for (i = 0; i < nvi; i += n) {
- ret = nilfs_palloc_get_entry_block(dat, vinfo[i].vi_vblocknr,
+ ret = nilfs_palloc_get_entry_block(dat, vinfo->vi_vblocknr,
0, &entry_bh);
if (ret < 0)
return ret;
kaddr = kmap_atomic(entry_bh->b_page, KM_USER0);
/* last virtual block number in this block */
- first = vinfo[i].vi_vblocknr;
+ first = vinfo->vi_vblocknr;
do_div(first, entries_per_block);
first *= entries_per_block;
last = first + entries_per_block - 1;
for (j = i, n = 0;
- j < nvi && vinfo[j].vi_vblocknr >= first &&
- vinfo[j].vi_vblocknr <= last;
- j++, n++) {
+ j < nvi && vinfo->vi_vblocknr >= first &&
+ vinfo->vi_vblocknr <= last;
+ j++, n++, vinfo = (void *)vinfo + visz) {
entry = nilfs_palloc_block_get_entry(
- dat, vinfo[j].vi_vblocknr, entry_bh, kaddr);
- vinfo[j].vi_start = le64_to_cpu(entry->de_start);
- vinfo[j].vi_end = le64_to_cpu(entry->de_end);
- vinfo[j].vi_blocknr = le64_to_cpu(entry->de_blocknr);
+ dat, vinfo->vi_vblocknr, entry_bh, kaddr);
+ vinfo->vi_start = le64_to_cpu(entry->de_start);
+ vinfo->vi_end = le64_to_cpu(entry->de_end);
+ vinfo->vi_blocknr = le64_to_cpu(entry->de_blocknr);
}
kunmap_atomic(kaddr, KM_USER0);
brelse(entry_bh);