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NFS: Fix put_nfs_open_context

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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: Trond Myklebust <Trond.Myklebust@netapp.com>
This commit is contained in:
Trond Myklebust 2007-07-26 12:06:17 -04:00
parent b247bbf1da
commit 5e11934d13
2 changed files with 9 additions and 17 deletions
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24
fs/nfs/inode.c
View file

@ -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);
struct inode *inode = ctx->path.dentry->d_inode;
if (!list_empty(&ctx->list)) {
struct inode *inode = ctx->path.dentry->d_inode;
spin_lock(&inode->i_lock);
list_del(&ctx->list);
spin_unlock(&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

2
include/linux/nfs_fs.h
View file

@ -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;