NFS: Allow the nfs_pageio_descriptor to signal that a re-coalesce is needed
If an attempt to do pNFS fails, and we have to fall back to writing through
the MDS, then we may want to re-coalesce the requests that we already have
since the block size for the MDS read/writes may be different to that of
the DS read/writes.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index d421e19..7139dbf 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -240,6 +240,7 @@
desc->pg_bsize = bsize;
desc->pg_base = 0;
desc->pg_moreio = 0;
+ desc->pg_recoalesce = 0;
desc->pg_inode = inode;
desc->pg_ops = pg_ops;
desc->pg_ioflags = io_flags;
@@ -331,7 +332,7 @@
* Returns true if the request 'req' was successfully coalesced into the
* existing list of pages 'desc'.
*/
-int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
+static int __nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
struct nfs_page *req)
{
while (!nfs_pageio_do_add_request(desc, req)) {
@@ -340,17 +341,67 @@
if (desc->pg_error < 0)
return 0;
desc->pg_moreio = 0;
+ if (desc->pg_recoalesce)
+ return 0;
}
return 1;
}
+static int nfs_do_recoalesce(struct nfs_pageio_descriptor *desc)
+{
+ LIST_HEAD(head);
+
+ do {
+ list_splice_init(&desc->pg_list, &head);
+ desc->pg_bytes_written -= desc->pg_count;
+ desc->pg_count = 0;
+ desc->pg_base = 0;
+ desc->pg_recoalesce = 0;
+
+ while (!list_empty(&head)) {
+ struct nfs_page *req;
+
+ req = list_first_entry(&head, struct nfs_page, wb_list);
+ nfs_list_remove_request(req);
+ if (__nfs_pageio_add_request(desc, req))
+ continue;
+ if (desc->pg_error < 0)
+ return 0;
+ break;
+ }
+ } while (desc->pg_recoalesce);
+ return 1;
+}
+
+int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
+ struct nfs_page *req)
+{
+ int ret;
+
+ do {
+ ret = __nfs_pageio_add_request(desc, req);
+ if (ret)
+ break;
+ if (desc->pg_error < 0)
+ break;
+ ret = nfs_do_recoalesce(desc);
+ } while (ret);
+ return ret;
+}
+
/**
* nfs_pageio_complete - Complete I/O on an nfs_pageio_descriptor
* @desc: pointer to io descriptor
*/
void nfs_pageio_complete(struct nfs_pageio_descriptor *desc)
{
- nfs_pageio_doio(desc);
+ for (;;) {
+ nfs_pageio_doio(desc);
+ if (!desc->pg_recoalesce)
+ break;
+ if (!nfs_do_recoalesce(desc))
+ break;
+ }
}
/**
@@ -369,7 +420,7 @@
if (!list_empty(&desc->pg_list)) {
struct nfs_page *prev = nfs_list_entry(desc->pg_list.prev);
if (index != prev->wb_index + 1)
- nfs_pageio_doio(desc);
+ nfs_pageio_complete(desc);
}
}
diff --git a/include/linux/nfs_page.h b/include/linux/nfs_page.h
index db3194f..7241b2a 100644
--- a/include/linux/nfs_page.h
+++ b/include/linux/nfs_page.h
@@ -68,7 +68,8 @@
size_t pg_count;
size_t pg_bsize;
unsigned int pg_base;
- char pg_moreio;
+ unsigned char pg_moreio : 1,
+ pg_recoalesce : 1;
struct inode *pg_inode;
const struct nfs_pageio_ops *pg_ops;
