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NFS: Optimise nfs_vm_page_mkwrite() 

The current model locks the page twice for no good reason. Optimise by
inlining the parts of nfs_write_begin()/nfs_write_end() that we care about.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
This commit is contained in:
Trond Myklebust 2008-01-22 17:13:06 -05:00
parent 77f111929d
commit 8b1f9ee56e
1 changed files with 15 additions and 23 deletions
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38
fs/nfs/file.c
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@ -392,35 +392,27 @@ static int nfs_vm_page_mkwrite(struct vm_area_struct *vma, struct page *page)
struct file *filp = vma->vm_file;
unsigned pagelen;
int ret = -EINVAL;
void *fsdata;
struct address_space *mapping;
loff_t offset;
lock_page(page);
mapping = page->mapping;
if (mapping != vma->vm_file->f_path.dentry->d_inode->i_mapping) {
unlock_page(page);
return -EINVAL;
}
if (mapping != vma->vm_file->f_path.dentry->d_inode->i_mapping)
goto out_unlock;
ret = 0;
pagelen = nfs_page_length(page);
offset = (loff_t)page->index << PAGE_CACHE_SHIFT;
if (pagelen == 0)
goto out_unlock;
ret = nfs_flush_incompatible(filp, page);
if (ret != 0)
goto out_unlock;
ret = nfs_updatepage(filp, page, 0, pagelen);
if (ret == 0)
ret = pagelen;
out_unlock:
unlock_page(page);
/*
* we can use mapping after releasing the page lock, because:
* we hold mmap_sem on the fault path, which should pin the vma
* which should pin the file, which pins the dentry which should
* hold a reference on inode.
*/
if (pagelen) {
struct page *page2 = NULL;
ret = nfs_write_begin(filp, mapping, offset, pagelen,
0, &page2, &fsdata);
if (!ret)
ret = nfs_write_end(filp, mapping, offset, pagelen,
pagelen, page2, fsdata);
}
return ret;
}