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NFS: Stop sillyname renames and unmounts from racing
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Added an active/deactive mechanism to the nfs_server structure
allowing async operations to hold off umount until the
operations are done.

Signed-off-by: Steve Dickson <steved@redhat.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
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Steve Dickson authored and Trond Myklebust committed Jan 30, 2008
1 parent 2f74c0a commit ef818a2
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Showing 5 changed files with 39 additions and 0 deletions.
3 changes: 3 additions & 0 deletions fs/nfs/client.c
Original file line number Diff line number Diff line change
Expand Up @@ -729,6 +729,9 @@ static struct nfs_server *nfs_alloc_server(void)
INIT_LIST_HEAD(&server->client_link);
INIT_LIST_HEAD(&server->master_link);

init_waitqueue_head(&server->active_wq);
atomic_set(&server->active, 0);

server->io_stats = nfs_alloc_iostats();
if (!server->io_stats) {
kfree(server);
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2 changes: 2 additions & 0 deletions fs/nfs/internal.h
Original file line number Diff line number Diff line change
Expand Up @@ -160,6 +160,8 @@ extern struct rpc_stat nfs_rpcstat;

extern int __init register_nfs_fs(void);
extern void __exit unregister_nfs_fs(void);
extern void nfs_sb_active(struct nfs_server *server);
extern void nfs_sb_deactive(struct nfs_server *server);

/* namespace.c */
extern char *nfs_path(const char *base,
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24 changes: 24 additions & 0 deletions fs/nfs/super.c
Original file line number Diff line number Diff line change
Expand Up @@ -202,6 +202,7 @@ static int nfs_get_sb(struct file_system_type *, int, const char *, void *, stru
static int nfs_xdev_get_sb(struct file_system_type *fs_type,
int flags, const char *dev_name, void *raw_data, struct vfsmount *mnt);
static void nfs_kill_super(struct super_block *);
static void nfs_put_super(struct super_block *);

static struct file_system_type nfs_fs_type = {
.owner = THIS_MODULE,
Expand All @@ -223,6 +224,7 @@ static const struct super_operations nfs_sops = {
.alloc_inode = nfs_alloc_inode,
.destroy_inode = nfs_destroy_inode,
.write_inode = nfs_write_inode,
.put_super = nfs_put_super,
.statfs = nfs_statfs,
.clear_inode = nfs_clear_inode,
.umount_begin = nfs_umount_begin,
Expand Down Expand Up @@ -325,6 +327,28 @@ void __exit unregister_nfs_fs(void)
unregister_filesystem(&nfs_fs_type);
}

void nfs_sb_active(struct nfs_server *server)
{
atomic_inc(&server->active);
}

void nfs_sb_deactive(struct nfs_server *server)
{
if (atomic_dec_and_test(&server->active))
wake_up(&server->active_wq);
}

static void nfs_put_super(struct super_block *sb)
{
struct nfs_server *server = NFS_SB(sb);
/*
* Make sure there are no outstanding ops to this server.
* If so, wait for them to finish before allowing the
* unmount to continue.
*/
wait_event(server->active_wq, atomic_read(&server->active) == 0);
}

/*
* Deliver file system statistics to userspace
*/
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4 changes: 4 additions & 0 deletions fs/nfs/unlink.c
Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,8 @@
#include <linux/sched.h>
#include <linux/wait.h>

#include "internal.h"

struct nfs_unlinkdata {
struct hlist_node list;
struct nfs_removeargs args;
Expand Down Expand Up @@ -113,6 +115,7 @@ static void nfs_async_unlink_release(void *calldata)
struct nfs_unlinkdata *data = calldata;

nfs_dec_sillycount(data->dir);
nfs_sb_deactive(NFS_SERVER(data->dir));
nfs_free_unlinkdata(data);
}

Expand Down Expand Up @@ -153,6 +156,7 @@ static int nfs_do_call_unlink(struct dentry *parent, struct inode *dir, struct n
nfs_dec_sillycount(dir);
return 0;
}
nfs_sb_active(NFS_SERVER(dir));
data->args.fh = NFS_FH(dir);
nfs_fattr_init(&data->res.dir_attr);

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6 changes: 6 additions & 0 deletions include/linux/nfs_fs_sb.h
Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,9 @@

#include <linux/list.h>
#include <linux/backing-dev.h>
#include <linux/wait.h>

#include <asm/atomic.h>

struct nfs_iostats;

Expand Down Expand Up @@ -110,6 +113,9 @@ struct nfs_server {
filesystem */
#endif
void (*destroy)(struct nfs_server *);

atomic_t active; /* Keep trace of any activity to this server */
wait_queue_head_t active_wq; /* Wait for any activity to stop */
};

/* Server capabilities */
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