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| author | Chuck Lever <chuck.lever@oracle.com> | 2006-09-20 14:33:04 -0400 |
|---|---|---|
| committer | Trond Myklebust <Trond.Myklebust@netapp.com> | 2006-09-22 23:25:05 -0400 |
| commit | f551e44ff11d3e2ec8f37907bb88ec2433cc8b74 (patch) | |
| tree | f86527c24391f70d72a28111df5c541959e8f293 | |
| parent | a53a3c58fd83e572a7c768d88b4c4e9840a57e82 (diff) | |
| download | linux-3.10-f551e44ff11d3e2ec8f37907bb88ec2433cc8b74.tar.gz linux-3.10-f551e44ff11d3e2ec8f37907bb88ec2433cc8b74.tar.bz2 linux-3.10-f551e44ff11d3e2ec8f37907bb88ec2433cc8b74.zip | |
NFS: add comments clarifying the use of nfs_post_op_update()
Comments-only change to clarify a detail of the NFS protocol and how it is
implemented in Linux.
Test plan:
None.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
| -rw-r--r-- | fs/nfs/inode.c | 6 | ||||
| -rw-r--r-- | fs/nfs/write.c | 8 |
2 files changed, 13 insertions, 1 deletions
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c index a56add0bc5b..e8c143d182c 100644 --- a/fs/nfs/inode.c +++ b/fs/nfs/inode.c @@ -840,6 +840,12 @@ int nfs_refresh_inode(struct inode *inode, struct nfs_fattr *fattr) * * After an operation that has changed the inode metadata, mark the * attribute cache as being invalid, then try to update it. + * + * NB: if the server didn't return any post op attributes, this + * function will force the retrieval of attributes before the next + * NFS request. Thus it should be used only for operations that + * are expected to change one or more attributes, to avoid + * unnecessary NFS requests and trips through nfs_update_inode(). */ int nfs_post_op_update_inode(struct inode *inode, struct nfs_fattr *fattr) { diff --git a/fs/nfs/write.c b/fs/nfs/write.c index 38ba5c09af0..c12effb46fe 100644 --- a/fs/nfs/write.c +++ b/fs/nfs/write.c @@ -1253,7 +1253,13 @@ int nfs_writeback_done(struct rpc_task *task, struct nfs_write_data *data) dprintk("NFS: %4d nfs_writeback_done (status %d)\n", task->tk_pid, task->tk_status); - /* Call the NFS version-specific code */ + /* + * ->write_done will attempt to use post-op attributes to detect + * conflicting writes by other clients. A strict interpretation + * of close-to-open would allow us to continue caching even if + * another writer had changed the file, but some applications + * depend on tighter cache coherency when writing. + */ status = NFS_PROTO(data->inode)->write_done(task, data); if (status != 0) return status; |