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NFSv4/pNFS: Fix another issue with a list iterator pointing to the head

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In nfs4_callback_devicenotify(), if we don't find a matching entry for
the deviceid, we're left with a pointer to 'struct nfs_server' that
actually points to the list of super blocks associated with our struct
nfs_client.
Furthermore, even if we have a valid pointer, nothing pins the super
block, and so the struct nfs_server could end up getting freed while
we're using it.

Since all we want is a pointer to the struct pnfs_layoutdriver_type,
let's skip all the iteration over super blocks, and just use APIs to
find the layout driver directly.

Reported-by: Xiaomeng Tong <xiam0nd.tong@gmail.com>
Fixes: 1be5683b03 ("pnfs: CB_NOTIFY_DEVICEID")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
This commit is contained in:
Trond Myklebust 2022-03-28 08:36:34 -04:00
parent d02d81efc7
commit 7c9d845f06
3 changed files with 22 additions and 18 deletions
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27
fs/nfs/callback_proc.c
View File

@ -358,12 +358,11 @@ __be32 nfs4_callback_devicenotify(void *argp, void *resp,
struct cb_process_state *cps)
{
struct cb_devicenotifyargs *args = argp;
const struct pnfs_layoutdriver_type *ld = NULL;
uint32_t i;
__be32 res = 0;
struct nfs_client *clp = cps->clp;
struct nfs_server *server = NULL;
if (!clp) {
if (!cps->clp) {
res = cpu_to_be32(NFS4ERR_OP_NOT_IN_SESSION);
goto out;
}
@ -371,23 +370,15 @@ __be32 nfs4_callback_devicenotify(void *argp, void *resp,
for (i = 0; i < args->ndevs; i++) {
struct cb_devicenotifyitem *dev = &args->devs[i];
if (!server ||
server->pnfs_curr_ld->id != dev->cbd_layout_type) {
rcu_read_lock();
list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
if (server->pnfs_curr_ld &&
server->pnfs_curr_ld->id == dev->cbd_layout_type) {
rcu_read_unlock();
goto found;
}
rcu_read_unlock();
continue;
if (!ld || ld->id != dev->cbd_layout_type) {
pnfs_put_layoutdriver(ld);
ld = pnfs_find_layoutdriver(dev->cbd_layout_type);
if (!ld)
continue;
}
found:
nfs4_delete_deviceid(server->pnfs_curr_ld, clp, &dev->cbd_dev_id);
nfs4_delete_deviceid(ld, cps->clp, &dev->cbd_dev_id);
}
pnfs_put_layoutdriver(ld);
out:
kfree(args->devs);
return res;

11
fs/nfs/pnfs.c
View File

@ -92,6 +92,17 @@ find_pnfs_driver(u32 id)
return local;
}
const struct pnfs_layoutdriver_type *pnfs_find_layoutdriver(u32 id)
{
return find_pnfs_driver(id);
}
void pnfs_put_layoutdriver(const struct pnfs_layoutdriver_type *ld)
{
if (ld)
module_put(ld->owner);
}
void
unset_pnfs_layoutdriver(struct nfs_server *nfss)
{

2
fs/nfs/pnfs.h
View File

@ -234,6 +234,8 @@ struct pnfs_devicelist {
extern int pnfs_register_layoutdriver(struct pnfs_layoutdriver_type *);
extern void pnfs_unregister_layoutdriver(struct pnfs_layoutdriver_type *);
extern const struct pnfs_layoutdriver_type *pnfs_find_layoutdriver(u32 id);
extern void pnfs_put_layoutdriver(const struct pnfs_layoutdriver_type *ld);
/* nfs4proc.c */
extern size_t max_response_pages(struct nfs_server *server);