Re: nfsd changes for 2.6.37

Arnd Bergmann
2010-10-27T13:46:28Z

On Wednesday 27 October 2010, J. Bruce Fields wrote:
> On Wed, Oct 27, 2010 at 04:39:24AM -0400, Christoph Hellwig wrote:
> > Do locks_alloc_lock and initialization of the heap struct file_lock
> > in the caller. This also avoids an entirely useless copy of the
> > lock structure. free the passed in structure if we are modifying
> > an existing lock structure.
>
> That sounds good; I'll give it a try.

I've already started, this is what I've come up with. I don't have
a good way to test it though, and don't know as much as you about this
code. Feel free to use it as a starting point if you like.
It does look correct to me, but I'm not very confident in this.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---

diff --git a/fs/locks.c b/fs/locks.c
index 8b2b6ad..c5ec771 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -162,10 +162,11 @@ EXPORT_SYMBOL_GPL(unlock_flocks);
static struct kmem_cache *filelock_cache __read_mostly;

/* Allocate an empty lock structure. */
-static struct file_lock *locks_alloc_lock(void)
+struct file_lock *locks_alloc_lock(void)
{
return kmem_cache_alloc(filelock_cache, GFP_KERNEL);
}
+EXPORT_SYMBOL_GPL(locks_alloc_lock);

void locks_release_private(struct file_lock *fl)
{
@@ -1365,7 +1366,6 @@ int fcntl_getlease(struct file *filp)
int generic_setlease(struct file *filp, long arg, struct file_lock **flp)
{
struct file_lock *fl, **before, **my_before = NULL, *lease;
- struct file_lock *new_fl = NULL;
struct dentry *dentry = filp->f_path.dentry;
struct inode *inode = dentry->d_inode;
int error, rdlease_count = 0, wrlease_count = 0;
@@ -1385,11 +1385,6 @@ int generic_setlease(struct file *filp, long arg, struct file_lock **flp)
lease = *flp;

if (arg != F_UNLCK) {
- error = -ENOMEM;
- new_fl = locks_alloc_lock();
- if (new_fl == NULL)
- goto out;
-
error = -EAGAIN;
if ((arg == F_RDLCK) && (atomic_read(&inode->i_writecount) > 0))
goto out;
@@ -1434,23 +1429,19 @@ int generic_setlease(struct file *filp, long arg, struct file_lock **flp)
goto out;
}

- error = 0;
if (arg == F_UNLCK)
- goto out;
+ goto out_unlck;

error = -EINVAL;
if (!leases_enable)
goto out;

- locks_copy_lock(new_fl, lease);
- locks_insert_lock(before, new_fl);
-
- *flp = new_fl;
+ locks_insert_lock(before, lease);
+out_unlck:
return 0;

out:
- if (new_fl != NULL)
- locks_free_lock(new_fl);
+ locks_free_lock(lease);
return error;
}
EXPORT_SYMBOL(generic_setlease);
@@ -1514,26 +1505,31 @@ EXPORT_SYMBOL_GPL(vfs_setlease);
*/
int fcntl_setlease(unsigned int fd, struct file *filp, long arg)
{
- struct file_lock fl, *flp = &fl;
+ struct file_lock *fl;
struct inode *inode = filp->f_path.dentry->d_inode;
int error;

- locks_init_lock(&fl);
- error = lease_init(filp, arg, &fl);
- if (error)
+ fl = locks_alloc_lock();
+ if (!fl)
+ return -ENOMEM;
+
+ locks_init_lock(fl);
+ error = lease_init(filp, arg, fl);
+ if (error) {
+ locks_free_lock(fl);
return error;
+ }

lock_flocks();
-
- error = __vfs_setlease(filp, arg, &flp);
+ error = __vfs_setlease(filp, arg, &fl);
if (error || arg == F_UNLCK)
goto out_unlock;

- error = fasync_helper(fd, filp, 1, &flp->fl_fasync);
+ error = fasync_helper(fd, filp, 1, &fl->fl_fasync);
if (error < 0) {
/* remove lease just inserted by setlease */
- flp->fl_type = F_UNLCK | F_INPROGRESS;
- flp->fl_break_time = jiffies - 10;
+ fl->fl_type = F_UNLCK | F_INPROGRESS;
+ fl->fl_break_time = jiffies - 10;
time_out_leases(inode);
goto out_unlock;
}
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 9019e8e..56347e0 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -2614,7 +2614,7 @@ nfs4_open_delegation(struct svc_fh *fh, struct nfsd4_open *open, struct nfs4_sta
struct nfs4_delegation *dp;
struct nfs4_stateowner *sop = stp->st_stateowner;
int cb_up = atomic_read(&sop->so_client->cl_cb_set);
- struct file_lock fl, *flp = &fl;
+ struct file_lock *fl;
int status, flag = 0;

flag = NFS4_OPEN_DELEGATE_NONE;
@@ -2648,20 +2648,24 @@ nfs4_open_delegation(struct svc_fh *fh, struct nfsd4_open *open, struct nfs4_sta
flag = NFS4_OPEN_DELEGATE_NONE;
goto out;
}
- locks_init_lock(&fl);
- fl.fl_lmops = &nfsd_lease_mng_ops;
- fl.fl_flags = FL_LEASE;
- fl.fl_type = flag == NFS4_OPEN_DELEGATE_READ? F_RDLCK: F_WRLCK;
- fl.fl_end = OFFSET_MAX;
- fl.fl_owner = (fl_owner_t)dp;
- fl.fl_file = find_readable_file(stp->st_file);
- BUG_ON(!fl.fl_file);
- fl.fl_pid = current->tgid;
+ status = -ENOMEM;
+ fl = locks_alloc_lock();
+ if (!fl)
+ goto out;
+ locks_init_lock(fl);
+ fl->fl_lmops = &nfsd_lease_mng_ops;
+ fl->fl_flags = FL_LEASE;
+ fl->fl_type = flag == NFS4_OPEN_DELEGATE_READ? F_RDLCK: F_WRLCK;
+ fl->fl_end = OFFSET_MAX;
+ fl->fl_owner = (fl_owner_t)dp;
+ fl->fl_file = find_readable_file(stp->st_file);
+ BUG_ON(!fl->fl_file);
+ fl->fl_pid = current->tgid;

/* vfs_setlease checks to see if delegation should be handed out.
* the lock_manager callbacks fl_mylease and fl_change are used
*/
- if ((status = vfs_setlease(fl.fl_file, fl.fl_type, &flp))) {
+ if ((status = vfs_setlease(fl->fl_file, fl->fl_type, &fl))) {
dprintk("NFSD: setlease failed [%d], no delegation\n", status);
unhash_delegation(dp);
flag = NFS4_OPEN_DELEGATE_NONE;