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[PATCH] NFS: Ensure that we revalidate the cached file length for llseek(SEEK_END) 

This fixes a data corruption error for mail delivery applications that
expect to be able to do posix locking and then append writes on NFS.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Trond Myklebust 2005-06-13 11:14:01 -04:00 committed by Linus Torvalds
parent c22fa3acbc
commit 980802e311
1 changed files with 41 additions and 1 deletions
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42
fs/nfs/file.c
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@ -37,6 +37,7 @@
static int nfs_file_open(struct inode *, struct file *);
static int nfs_file_release(struct inode *, struct file *);
static loff_t nfs_file_llseek(struct file *file, loff_t offset, int origin);
static int nfs_file_mmap(struct file *, struct vm_area_struct *);
static ssize_t nfs_file_sendfile(struct file *, loff_t *, size_t, read_actor_t, void *);
static ssize_t nfs_file_read(struct kiocb *, char __user *, size_t, loff_t);
@ -48,7 +49,7 @@ 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);
struct file_operations nfs_file_operations = {
.llseek = remote_llseek,
.llseek = nfs_file_llseek,
.read = do_sync_read,
.write = do_sync_write,
.aio_read = nfs_file_read,
@ -114,6 +115,45 @@ nfs_file_release(struct inode *inode, struct file *filp)
return NFS_PROTO(inode)->file_release(inode, filp);
}
/**
* nfs_revalidate_size - Revalidate the file size
* @inode - pointer to inode struct
* @file - pointer to struct file
*
* Revalidates the file length. This is basically a wrapper around
* nfs_revalidate_inode() that takes into account the fact that we may
* have cached writes (in which case we don't care about the server's
* idea of what the file length is), or O_DIRECT (in which case we
* shouldn't trust the cache).
*/
static int nfs_revalidate_file_size(struct inode *inode, struct file *filp)
{
struct nfs_server *server = NFS_SERVER(inode);
struct nfs_inode *nfsi = NFS_I(inode);
if (server->flags & NFS_MOUNT_NOAC)
goto force_reval;
if (filp->f_flags & O_DIRECT)
goto force_reval;
if (nfsi->npages != 0)
return 0;
return nfs_revalidate_inode(server, inode);
force_reval:
return __nfs_revalidate_inode(server, inode);
}
static loff_t nfs_file_llseek(struct file *filp, loff_t offset, int origin)
{
/* origin == SEEK_END => we must revalidate the cached file length */
if (origin == 2) {
struct inode *inode = filp->f_mapping->host;
int retval = nfs_revalidate_file_size(inode, filp);
if (retval < 0)
return (loff_t)retval;
}
return remote_llseek(filp, offset, origin);
}
/*
* Flush all dirty pages, and check for write errors.
*