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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

21
fs/nilfs2/dat.c
View File

@@ -376,36 +376,37 @@ int nilfs_dat_translate(struct inode *dat, __u64 vblocknr, sector_t *blocknrp)
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);