J. Bruce Fields wrote:
From: J. Bruce Fields <bfields@xxxxxxxxxxxxxx>
As Peter Staubach says elsewhere
(http://marc.info/?l=linux-kernel&m=118113649526444&w=2):
The problem is that some file system such as NFSv2 and NFSv3 do
not have sufficient support to be able to support leases correctly.
In particular for these two file systems, there is no over the wire
protocol support.
Currently, these two file systems fail the fcntl(F_SETLEASE) call
accidentally, due to a reference counting difference. These file
systems should fail more consciously, with a proper error to
indicate that the call is invalid for them.
Define an nfs setlease method that just returns -EOPNOTSUPP.
If someone can demonstrate a real need, perhaps we could reenable
them in the presence of the "nolock" mount option.
Signed-off-by: "J. Bruce Fields" <bfields@xxxxxxxxxxxxxx>
Cc: Peter Staubach <staubach@xxxxxxxxxx>
Cc: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>
---
fs/nfs/file.c | 7 +++++++
1 files changed, 7 insertions(+), 0 deletions(-)
diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index 9eb8eb4..97c1a3d 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -51,6 +51,7 @@ static int nfs_fsync(struct file *, struct dentry *dentry, int datasync);
static int nfs_check_flags(int flags);
static int nfs_lock(struct file *filp, int cmd, struct file_lock *fl);
static int nfs_flock(struct file *filp, int cmd, struct file_lock *fl);
+static int nfs_setlease(struct file *file, long arg, struct file_lock **fl);
const struct file_operations nfs_file_operations = {
.llseek = nfs_file_llseek,
@@ -67,6 +68,7 @@ const struct file_operations nfs_file_operations = {
.flock = nfs_flock,
.sendfile = nfs_file_sendfile,
.check_flags = nfs_check_flags,
+ .setlease = nfs_setlease,
};
const struct inode_operations nfs_file_inode_operations = {
@@ -555,3 +557,8 @@ static int nfs_flock(struct file *filp, int cmd, struct file_lock *fl)
return do_unlk(filp, cmd, fl);
return do_setlk(filp, cmd, fl);
}
+
+static int nfs_setlease(struct file *file, long arg, struct file_lock **fl)
+{
+ return -EOPNOTSUPP;
+}
A couple of things --
First, there is already some support to disable leases for NFS mounted
file systems in -mm, I think. Are you planning on removing it?
Second, it seems to me that EINVAL would be a better error to return
than EOPNOTSUPP. This is an invalid operation to apply to this file
and might match POSIX style specs better.
Thanx...
ps
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