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NFS: Allow nfs_updatepage to extend a write under additional circumstances

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Currently nfs_updatepage allows a write to be extended to cover a full
page only if we don't have a byte range lock lock on the file... but if
we have a write delegation on the file or if we have the whole file
locked for writing then we should be allowed to extend the write as
well.

Signed-off-by: Scott Mayhew <smayhew@redhat.com>
[Trond: fix up call to nfs_have_delegation()]
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
This commit is contained in:
Scott Mayhew 2013-07-05 17:33:19 -04:00 committed by Trond Myklebust
parent 07b5ce8ef2
commit c7559663e4
1 changed files with 23 additions and 8 deletions
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31
fs/nfs/write.c
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@ -888,6 +888,28 @@ out:
return PageUptodate(page) != 0;
}
/* If we know the page is up to date, and we're not using byte range locks (or
* if we have the whole file locked for writing), it may be more efficient to
* extend the write to cover the entire page in order to avoid fragmentation
* inefficiencies.
*
* If the file is opened for synchronous writes or if we have a write delegation
* from the server then we can just skip the rest of the checks.
*/
static int nfs_can_extend_write(struct file *file, struct page *page, struct inode *inode)
{
if (file->f_flags & O_DSYNC)
return 0;
if (NFS_PROTO(inode)->have_delegation(inode, FMODE_WRITE))
return 1;
if (nfs_write_pageuptodate(page, inode) && (inode->i_flock == NULL ||
(inode->i_flock->fl_start == 0 &&
inode->i_flock->fl_end == OFFSET_MAX &&
inode->i_flock->fl_type != F_RDLCK)))
return 1;
return 0;
}
/*
* Update and possibly write a cached page of an NFS file.
*
@ -908,14 +930,7 @@ int nfs_updatepage(struct file *file, struct page *page,
file->f_path.dentry->d_name.name, count,
(long long)(page_file_offset(page) + offset));
/* If we're not using byte range locks, and we know the page
* is up to date, it may be more efficient to extend the write
* to cover the entire page in order to avoid fragmentation
* inefficiencies.
*/
if (nfs_write_pageuptodate(page, inode) &&
inode->i_flock == NULL &&
!(file->f_flags & O_DSYNC)) {
if (nfs_can_extend_write(file, page, inode)) {
count = max(count + offset, nfs_page_length(page));
offset = 0;
}