NFS: Cleanup the coalescing code
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index ca4b1d4..7017eb0 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -223,48 +223,101 @@
}
/**
- * nfs_coalesce_requests - Split coalesced requests out from a list.
+ * nfs_pageio_init - initialise a page io descriptor
+ * @desc: pointer to descriptor
+ * @iosize: io block size
+ */
+void nfs_pageio_init(struct nfs_pageio_descriptor *desc, unsigned int bsize)
+{
+ INIT_LIST_HEAD(&desc->pg_list);
+ desc->pg_count = 0;
+ desc->pg_bsize = bsize;
+ desc->pg_base = 0;
+}
+
+/**
+ * nfs_can_coalesce_requests - test two requests for compatibility
+ * @prev: pointer to nfs_page
+ * @req: pointer to nfs_page
+ *
+ * The nfs_page structures 'prev' and 'req' are compared to ensure that the
+ * page data area they describe is contiguous, and that their RPC
+ * credentials, NFSv4 open state, and lockowners are the same.
+ *
+ * Return 'true' if this is the case, else return 'false'.
+ */
+static int nfs_can_coalesce_requests(struct nfs_page *prev,
+ struct nfs_page *req)
+{
+ if (req->wb_context->cred != prev->wb_context->cred)
+ return 0;
+ if (req->wb_context->lockowner != prev->wb_context->lockowner)
+ return 0;
+ if (req->wb_context->state != prev->wb_context->state)
+ return 0;
+ if (req->wb_index != (prev->wb_index + 1))
+ return 0;
+ if (req->wb_pgbase != 0)
+ return 0;
+ if (prev->wb_pgbase + prev->wb_bytes != PAGE_CACHE_SIZE)
+ return 0;
+ return 1;
+}
+
+/**
+ * nfs_pageio_add_request - Attempt to coalesce a request into a page list.
+ * @desc: destination io descriptor
+ * @req: request
+ *
+ * Returns true if the request 'req' was successfully coalesced into the
+ * existing list of pages 'desc'.
+ */
+static int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
+ struct nfs_page *req)
+{
+ size_t newlen = req->wb_bytes;
+
+ if (desc->pg_count != 0) {
+ struct nfs_page *prev;
+
+ /*
+ * FIXME: ideally we should be able to coalesce all requests
+ * that are not block boundary aligned, but currently this
+ * is problematic for the case of bsize < PAGE_CACHE_SIZE,
+ * since nfs_flush_multi and nfs_pagein_multi assume you
+ * can have only one struct nfs_page.
+ */
+ newlen += desc->pg_count;
+ if (desc->pg_base + newlen > desc->pg_bsize)
+ return 0;
+ prev = nfs_list_entry(desc->pg_list.prev);
+ if (!nfs_can_coalesce_requests(prev, req))
+ return 0;
+ } else
+ desc->pg_base = req->wb_pgbase;
+ nfs_list_remove_request(req);
+ nfs_list_add_request(req, &desc->pg_list);
+ desc->pg_count = newlen;
+ return 1;
+}
+
+/**
+ * nfs_pageio_add_list - Split coalesced requests out from a list.
+ * @desc: destination io descriptor
* @head: source list
- * @dst: destination list
- * @nmax: maximum number of requests to coalesce
*
* Moves a maximum of 'nmax' elements from one list to another.
* The elements are checked to ensure that they form a contiguous set
* of pages, and that the RPC credentials are the same.
*/
-int
-nfs_coalesce_requests(struct list_head *head, struct list_head *dst,
- unsigned int nmax)
+void nfs_pageio_add_list(struct nfs_pageio_descriptor *desc,
+ struct list_head *head)
{
- struct nfs_page *req = NULL;
- unsigned int npages = 0;
-
while (!list_empty(head)) {
- struct nfs_page *prev = req;
-
- req = nfs_list_entry(head->next);
- if (prev) {
- if (req->wb_context->cred != prev->wb_context->cred)
- break;
- if (req->wb_context->lockowner != prev->wb_context->lockowner)
- break;
- if (req->wb_context->state != prev->wb_context->state)
- break;
- if (req->wb_index != (prev->wb_index + 1))
- break;
-
- if (req->wb_pgbase != 0)
- break;
- }
- nfs_list_remove_request(req);
- nfs_list_add_request(req, dst);
- npages++;
- if (req->wb_pgbase + req->wb_bytes != PAGE_CACHE_SIZE)
- break;
- if (npages >= nmax)
+ struct nfs_page *req = nfs_list_entry(head->next);
+ if (!nfs_pageio_add_request(desc, req))
break;
}
- return npages;
}
#define NFS_SCAN_MAXENTRIES 16
diff --git a/fs/nfs/read.c b/fs/nfs/read.c
index 6ab4d5a..97f0f42 100644
--- a/fs/nfs/read.c
+++ b/fs/nfs/read.c
@@ -328,24 +328,26 @@
}
static int
-nfs_pagein_list(struct list_head *head, int rpages)
+nfs_pagein_list(struct list_head *head, unsigned int rsize)
{
- LIST_HEAD(one_request);
- struct nfs_page *req;
- int error = 0;
- unsigned int pages = 0;
+ struct nfs_pageio_descriptor desc;
+ struct nfs_page *req;
+ unsigned int pages = 0;
+ int error = 0;
while (!list_empty(head)) {
- pages += nfs_coalesce_requests(head, &one_request, rpages);
- req = nfs_list_entry(one_request.next);
- error = nfs_pagein_one(&one_request, req->wb_context->dentry->d_inode);
+ nfs_pageio_init(&desc, rsize);
+ nfs_pageio_add_list(&desc, head);
+ req = nfs_list_entry(desc.pg_list.next);
+ error = nfs_pagein_one(&desc.pg_list, req->wb_context->dentry->d_inode);
if (error < 0)
break;
+ pages += (desc.pg_count + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
}
- if (error >= 0)
- return pages;
nfs_async_read_error(head);
+ if (error >= 0)
+ return pages;
return error;
}
@@ -595,7 +597,7 @@
filp->private_data);
ret = read_cache_pages(mapping, pages, readpage_async_filler, &desc);
if (!list_empty(&head)) {
- int err = nfs_pagein_list(&head, server->rpages);
+ int err = nfs_pagein_list(&head, server->rsize);
if (!ret)
nfs_add_stats(inode, NFSIOS_READPAGES, err);
ret = err;
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index dbad89c..b03ec1ba 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -945,9 +945,8 @@
static int nfs_flush_list(struct inode *inode, struct list_head *head, int npages, int how)
{
- LIST_HEAD(one_request);
+ struct nfs_pageio_descriptor desc;
int (*flush_one)(struct inode *, struct list_head *, int);
- struct nfs_page *req;
int wpages = NFS_SERVER(inode)->wpages;
int wsize = NFS_SERVER(inode)->wsize;
int error;
@@ -961,16 +960,16 @@
how |= FLUSH_STABLE;
do {
- nfs_coalesce_requests(head, &one_request, wpages);
- req = nfs_list_entry(one_request.next);
- error = flush_one(inode, &one_request, how);
+ nfs_pageio_init(&desc, wsize);
+ nfs_pageio_add_list(&desc, head);
+ error = flush_one(inode, &desc.pg_list, how);
if (error < 0)
goto out_err;
} while (!list_empty(head));
return 0;
out_err:
while (!list_empty(head)) {
- req = nfs_list_entry(head->next);
+ struct nfs_page *req = nfs_list_entry(head->next);
nfs_list_remove_request(req);
nfs_redirty_request(req);
nfs_end_page_writeback(req->wb_page);
diff --git a/include/linux/nfs_page.h b/include/linux/nfs_page.h
index 16b0266..3ef8e04 100644
--- a/include/linux/nfs_page.h
+++ b/include/linux/nfs_page.h
@@ -48,6 +48,13 @@
struct nfs_writeverf wb_verf; /* Commit cookie */
};
+struct nfs_pageio_descriptor {
+ struct list_head pg_list;
+ size_t pg_count;
+ size_t pg_bsize;
+ unsigned int pg_base;
+};
+
#define NFS_WBACK_BUSY(req) (test_bit(PG_BUSY,&(req)->wb_flags))
extern struct nfs_page *nfs_create_request(struct nfs_open_context *ctx,
@@ -64,8 +71,10 @@
struct list_head *dst);
extern int nfs_scan_list(struct nfs_inode *nfsi, struct list_head *head, struct list_head *dst,
unsigned long idx_start, unsigned int npages);
-extern int nfs_coalesce_requests(struct list_head *, struct list_head *,
- unsigned int);
+extern void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
+ size_t iosize);
+extern void nfs_pageio_add_list(struct nfs_pageio_descriptor *,
+ struct list_head *);
extern int nfs_wait_on_request(struct nfs_page *);
extern void nfs_unlock_request(struct nfs_page *req);
extern int nfs_set_page_writeback_locked(struct nfs_page *req);