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Commit 5e11934d authored by Trond Myklebust's avatar Trond Myklebust
Browse files

NFS: Fix put_nfs_open_context 



We need to grab the inode->i_lock atomically with the last reference put in
order to remove the open context that is being freed from the
nfsi->open_files list.

Fix by converting the kref to a standard atomic counter and then using
atomic_dec_and_lock()...

Thanks to Arnd Bergmann for pointing out the problem.

Signed-off-by: default avatarTrond Myklebust <Trond.Myklebust@netapp.com>
parent b247bbf1

fs/nfs/inode.c

+8 −16
Original line number Diff line number Diff line
@@ -468,7 +468,7 @@ static struct nfs_open_context *alloc_nfs_open_context(struct vfsmount *mnt, str 
		ctx->lockowner = current->files;

		ctx->error = 0;

		ctx->dir_cookie = 0;

		kref_init(&ctx->kref);

		atomic_set(&ctx->count, 1);

	}

	return ctx;

}
@@ -476,21 +476,18 @@ static struct nfs_open_context *alloc_nfs_open_context(struct vfsmount *mnt, str 
struct nfs_open_context *get_nfs_open_context(struct nfs_open_context *ctx)

{

	if (ctx != NULL)

		kref_get(&ctx->kref);

		atomic_inc(&ctx->count);

	return ctx;

}



static void nfs_free_open_context(struct kref *kref)

void put_nfs_open_context(struct nfs_open_context *ctx)

{

	struct nfs_open_context *ctx = container_of(kref,

			struct nfs_open_context, kref);



	if (!list_empty(&ctx->list)) {

	struct inode *inode = ctx->path.dentry->d_inode;

		spin_lock(&inode->i_lock);



	if (!atomic_dec_and_lock(&ctx->count, &inode->i_lock))

		return;

	list_del(&ctx->list);

	spin_unlock(&inode->i_lock);

	}

	if (ctx->state != NULL)

		nfs4_close_state(&ctx->path, ctx->state, ctx->mode);

	if (ctx->cred != NULL)
@@ -500,11 +497,6 @@ static void nfs_free_open_context(struct kref *kref) 
	kfree(ctx);

}



void put_nfs_open_context(struct nfs_open_context *ctx)

{

	kref_put(&ctx->kref, nfs_free_open_context);

}



/*

 * Ensure that mmap has a recent RPC credential for use when writing out

 * shared pages

include/linux/nfs_fs.h

+1 −1
Original line number Diff line number Diff line
@@ -71,7 +71,7 @@ struct nfs_access_entry { 


struct nfs4_state;

struct nfs_open_context {

	struct kref kref;

	atomic_t count;

	struct path path;

	struct rpc_cred *cred;

	struct nfs4_state *state;