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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>
This commit is contained in:
Trond Myklebust 2011-07-12 13:42:02 -04:00
parent d097971d8a
commit d9156f9f36
2 changed files with 56 additions and 4 deletions
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57
fs/nfs/pagelist.c
View File

@ -240,6 +240,7 @@ void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
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 @@ static void nfs_pageio_doio(struct nfs_pageio_descriptor *desc)
* 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 @@ int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
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 @@ void nfs_pageio_cond_complete(struct nfs_pageio_descriptor *desc, pgoff_t index)
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);
}
}

3
include/linux/nfs_page.h
View File

@ -68,7 +68,8 @@ struct nfs_pageio_descriptor {
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;