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pNFS: Delay getting the layout header in CB_LAYOUTRECALL handlers

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Instead of grabbing the layout, we want to get the inode so that we
can reduce races between layoutget and layoutrecall when the server
does not support call referring.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
This commit is contained in:
Trond Myklebust 2016-10-31 10:05:21 -04:00
parent 17822b207f
commit 7b410d9ce4
1 changed files with 68 additions and 33 deletions
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101
fs/nfs/callback_proc.c
View File

@ -110,20 +110,52 @@ out:
#if defined(CONFIG_NFS_V4_1)
/*
* Lookup a layout by filehandle.
* Lookup a layout inode by stateid
*
* Note: gets a refcount on the layout hdr and on its respective inode.
* Caller must put the layout hdr and the inode.
*
* TODO: keep track of all layouts (and delegations) in a hash table
* hashed by filehandle.
* Note: returns a refcount on the inode and superblock
*/
static struct pnfs_layout_hdr * get_layout_by_fh_locked(struct nfs_client *clp,
struct nfs_fh *fh)
static struct inode *nfs_layout_find_inode_by_stateid(struct nfs_client *clp,
const nfs4_stateid *stateid)
{
struct nfs_server *server;
struct inode *inode;
struct pnfs_layout_hdr *lo;
restart:
list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
list_for_each_entry(lo, &server->layouts, plh_layouts) {
if (stateid != NULL &&
!nfs4_stateid_match_other(stateid, &lo->plh_stateid))
continue;
inode = igrab(lo->plh_inode);
if (!inode)
continue;
if (!nfs_sb_active(inode->i_sb)) {
rcu_read_lock();
spin_unlock(&clp->cl_lock);
iput(inode);
spin_lock(&clp->cl_lock);
goto restart;
}
return inode;
}
}
return NULL;
}
/*
* Lookup a layout inode by filehandle.
*
* Note: returns a refcount on the inode and superblock
*
*/
static struct inode *nfs_layout_find_inode_by_fh(struct nfs_client *clp,
const struct nfs_fh *fh)
{
struct nfs_server *server;
struct nfs_inode *nfsi;
struct inode *ino;
struct inode *inode;
struct pnfs_layout_hdr *lo;
restart:
@ -134,37 +166,38 @@ restart:
continue;
if (nfsi->layout != lo)
continue;
ino = igrab(lo->plh_inode);
if (!ino)
break;
spin_lock(&ino->i_lock);
/* Is this layout in the process of being freed? */
if (nfsi->layout != lo) {
spin_unlock(&ino->i_lock);
iput(ino);
inode = igrab(lo->plh_inode);
if (!inode)
continue;
if (!nfs_sb_active(inode->i_sb)) {
rcu_read_lock();
spin_unlock(&clp->cl_lock);
iput(inode);
spin_lock(&clp->cl_lock);
goto restart;
}
pnfs_get_layout_hdr(lo);
spin_unlock(&ino->i_lock);
return lo;
return inode;
}
}
return NULL;
}
static struct pnfs_layout_hdr * get_layout_by_fh(struct nfs_client *clp,
struct nfs_fh *fh)
static struct inode *nfs_layout_find_inode(struct nfs_client *clp,
const struct nfs_fh *fh,
const nfs4_stateid *stateid)
{
struct pnfs_layout_hdr *lo;
struct inode *inode;
spin_lock(&clp->cl_lock);
rcu_read_lock();
lo = get_layout_by_fh_locked(clp, fh);
inode = nfs_layout_find_inode_by_stateid(clp, stateid);
if (!inode)
inode = nfs_layout_find_inode_by_fh(clp, fh);
rcu_read_unlock();
spin_unlock(&clp->cl_lock);
return lo;
return inode;
}
/*
@ -213,18 +246,20 @@ static u32 initiate_file_draining(struct nfs_client *clp,
u32 rv = NFS4ERR_NOMATCHING_LAYOUT;
LIST_HEAD(free_me_list);
lo = get_layout_by_fh(clp, &args->cbl_fh);
if (!lo) {
trace_nfs4_cb_layoutrecall_file(clp, &args->cbl_fh, NULL,
&args->cbl_stateid, -rv);
ino = nfs_layout_find_inode(clp, &args->cbl_fh, &args->cbl_stateid);
if (!ino)
goto out;
}
ino = lo->plh_inode;
pnfs_layoutcommit_inode(ino, false);
spin_lock(&ino->i_lock);
lo = NFS_I(ino)->layout;
if (!lo) {
spin_unlock(&ino->i_lock);
goto out;
}
pnfs_get_layout_hdr(lo);
rv = pnfs_check_callback_stateid(lo, &args->cbl_stateid);
if (rv != NFS_OK)
goto unlock;
@ -258,10 +293,10 @@ unlock:
/* Free all lsegs that are attached to commit buckets */
nfs_commit_inode(ino, 0);
pnfs_put_layout_hdr(lo);
out:
trace_nfs4_cb_layoutrecall_file(clp, &args->cbl_fh, ino,
&args->cbl_stateid, -rv);
iput(ino);
out:
nfs_iput_and_deactive(ino);
return rv;
}