ty den 11.10.2005 Klokka 11:09 (+0200) skreiv Leif Nixon:
> Hi,
>
> We have come across a bug where a NFS v3 client fails to invalidate
> its data cache for a file even though it realizes that the file
> attributes have changed. We have been able to recreate the bug on a
> range of kernel versions and different underlying file systems.
>
> Here's a minimal way to reproduce the error (there seems to be some
> timing issues involved, but this has worked at least 90% of the time):
>
> NFS client n1 NFS client n2
>
> $ echo 1 > f
> $ cat f
> 1
> $ touch .
> $ echo 2 > f
> $ touch f
> $ cat f
> 1
>
> Now client n2 is stuck in a state where it uses its old cached data
> forever (or at least for several hours):
>
> NFS client n1 NFS client n2
>
> $ cat f
> 2
> $ cat f
> 1
>
> However, "stat f" gives the same output on both clients. "touch f" on
> either machine corrects the situation; n2 invalidates its data cache.
>
> Interestingly, the second write to the file ("echo 2 > f") must
> not change the size of the file. If you do "echo foo > f" instead,
> the erroneous behaviour isn't triggered.
>
> We have seen this on a range of kernels between 2.6.9 and 2.6.13.2 on
> Debian, CentOS, RHEL, Fedora and vanilla kernel.org, on both clients
> and server. We have *not* been able to reproduce the bug with Linux
> clients and a Solaris server, neither with Solaris clients and a Linux
> server. Underlying file systems have been ext3 and xfs (and Solaris
> ufs). We have tried varying mount options, but to no avail; the bug
> persists, even with "noac".
Does the attached patch help?
Cheers,
Trond
NFS: Fix cache consistency races
If the data cache has been marked as potentially invalid by nfs_refresh_inode,
we should invalidate it rather than assume that changes are due to our own
activity.
Also ensure that we always start with a valid cache before declaring it
to be protected by a delegation.
Signed-off-by: Trond Myklebust <[email protected]>
---
delegation.c | 4 ++++
file.c | 3 ++-
inode.c | 7 ++-----
3 files changed, 8 insertions(+), 6 deletions(-)
Index: linux-2.6.14-rc4/fs/nfs/delegation.c
===================================================================
--- linux-2.6.14-rc4.orig/fs/nfs/delegation.c
+++ linux-2.6.14-rc4/fs/nfs/delegation.c
@@ -85,6 +85,10 @@ int nfs_inode_set_delegation(struct inod
struct nfs_delegation *delegation;
int status = 0;
+ /* Ensure we first revalidate the attributes and page cache! */
+ if ((nfsi->cache_validity & (NFS_INO_REVAL_PAGECACHE|NFS_INO_INVALID_ATTR)))
+ __nfs_revalidate_inode(NFS_SERVER(inode), inode);
+
delegation = nfs_alloc_delegation();
if (delegation == NULL)
return -ENOMEM;
Index: linux-2.6.14-rc4/fs/nfs/file.c
===================================================================
--- linux-2.6.14-rc4.orig/fs/nfs/file.c
+++ linux-2.6.14-rc4/fs/nfs/file.c
@@ -137,7 +137,8 @@ static int nfs_revalidate_file(struct in
struct nfs_inode *nfsi = NFS_I(inode);
int retval = 0;
- if ((nfsi->cache_validity & NFS_INO_REVAL_PAGECACHE) || nfs_attribute_timeout(inode))
+ if ((nfsi->cache_validity & (NFS_INO_REVAL_PAGECACHE|NFS_INO_INVALID_ATTR))
+ || nfs_attribute_timeout(inode))
retval = __nfs_revalidate_inode(NFS_SERVER(inode), inode);
nfs_revalidate_mapping(inode, filp->f_mapping);
return 0;
Index: linux-2.6.14-rc4/fs/nfs/inode.c
===================================================================
--- linux-2.6.14-rc4.orig/fs/nfs/inode.c
+++ linux-2.6.14-rc4/fs/nfs/inode.c
@@ -1226,10 +1226,6 @@ int nfs_refresh_inode(struct inode *inod
loff_t cur_size, new_isize;
int data_unstable;
- /* Do we hold a delegation? */
- if (nfs_have_delegation(inode, FMODE_READ))
- return 0;
-
spin_lock(&inode->i_lock);
/* Are we in the process of updating data on the server? */
@@ -1350,7 +1346,8 @@ static int nfs_update_inode(struct inode
nfsi->read_cache_jiffies = fattr->timestamp;
/* Are we racing with known updates of the metadata on the server? */
- data_unstable = ! nfs_verify_change_attribute(inode, verifier);
+ data_unstable = ! (nfs_verify_change_attribute(inode, verifier) ||
+ (nfsi->cache_validity & NFS_INO_REVAL_PAGECACHE));
/* Check if our cached file size is stale */
new_isize = nfs_size_to_loff_t(fattr->size);
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