static struct nfs_page *nfs_find_and_lock_request(struct page *page)
{
struct inode *inode = page->mapping->host;
struct nfs_page *req;
int ret;
spin_lock(&inode->i_lock);
for (;;) {
req = nfs_page_find_request_locked(page);
if (req == NULL)
break;
if (nfs_set_page_tag_locked(req))
break;
/* Note: If we hold the page lock, as is the case in nfs_writepage,
* then the call to nfs_set_page_tag_locked() will always
* succeed provided that someone hasn't already marked the
* request as dirty (in which case we don't care).
*/
spin_unlock(&inode->i_lock);
ret = nfs_wait_on_request(req);
nfs_release_request(req);
if (ret != 0)
return ERR_PTR(ret);
spin_lock(&inode->i_lock);
}
spin_unlock(&inode->i_lock);
return req;
}
static struct nfs_page *nfs_page_find_request(struct page *page)
{
struct inode *inode = page->mapping->host;
struct nfs_page *req = NULL;
spin_lock(&inode->i_lock);
req = nfs_page_find_request_locked(page);
spin_unlock(&inode->i_lock);
return req;
}
/*
* Find an associated nfs write request, and prepare to flush it out
* May return an error if the user signalled nfs_wait_on_request().
*/
static int nfs_page_async_flush(struct nfs_pageio_descriptor *pgio,
struct page *page)
{
struct inode *inode = page->mapping->host;
struct nfs_page *req;
int ret;
spin_lock(&inode->i_lock);
for(;;) {
req = nfs_page_find_request_locked(page);
if (req == NULL) {
spin_unlock(&inode->i_lock);
return 0;
}
if (nfs_set_page_tag_locked(req))
break;
/* Note: If we hold the page lock, as is the case in nfs_writepage,
* then the call to nfs_set_page_tag_locked() will always
* succeed provided that someone hasn't already marked the
* request as dirty (in which case we don't care).
*/
spin_unlock(&inode->i_lock);
ret = nfs_wait_on_request(req);
nfs_release_request(req);
if (ret != 0)
return ret;
spin_lock(&inode->i_lock);
}
if (test_bit(PG_CLEAN, &req->wb_flags)) {
spin_unlock(&inode->i_lock);
BUG();
}
if (nfs_set_page_writeback(page) != 0) {
spin_unlock(&inode->i_lock);
BUG();
}
spin_unlock(&inode->i_lock);
if (!nfs_pageio_add_request(pgio, req)) {
nfs_redirty_request(req);
return pgio->pg_error;
}
return 0;
}
/*
* Search for an existing write request, and attempt to update
* it to reflect a new dirty region on a given page.
*
* If the attempt fails, then the existing request is flushed out
* to disk.
*/
static struct nfs_page *nfs_try_to_update_request(struct inode *inode,
struct page *page,
unsigned int offset,
unsigned int bytes)
{
struct nfs_page *req;
unsigned int rqend;
unsigned int end;
int error;
if (!PagePrivate(page))
return NULL;
end = offset + bytes;
spin_lock(&inode->i_lock);
for (;;) {
req = nfs_page_find_request_locked(page);
if (req == NULL)
goto out_unlock;
rqend = req->wb_offset + req->wb_bytes;
/*
* Tell the caller to flush out the request if
* the offsets are non-contiguous.
* Note: nfs_flush_incompatible() will already
* have flushed out requests having wrong owners.
*/
if (offset > rqend
|| end < req->wb_offset)
goto out_flushme;
if (nfs_set_page_tag_locked(req))
break;
/* The request is locked, so wait and then retry */
spin_unlock(&inode->i_lock);
error = nfs_wait_on_request(req);
nfs_release_request(req);
if (error != 0)
goto out_err;
spin_lock(&inode->i_lock);
}
if (nfs_clear_request_commit(req))
radix_tree_tag_clear(&NFS_I(inode)->nfs_page_tree,
req->wb_index, NFS_PAGE_TAG_COMMIT);
/* Okay, the request matches. Update the region */
if (offset < req->wb_offset) {
req->wb_offset = offset;
req->wb_pgbase = offset;
}
if (end > rqend)
req->wb_bytes = end - req->wb_offset;
else
req->wb_bytes = rqend - req->wb_offset;
out_unlock:
spin_unlock(&inode->i_lock);
return req;
out_flushme:
spin_unlock(&inode->i_lock);
nfs_release_request(req);
error = nfs_wb_page(inode, page);
out_err:
return ERR_PTR(error);
}
