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authorChuck Lever <cel@netapp.com>2006-06-20 12:56:49 -0400
committerTrond Myklebust <Trond.Myklebust@netapp.com>2006-06-24 13:11:39 -0400
commit06cf6f2ed0b19629700794727d86ed57b9c0583e (patch)
tree20630465974dc9391af486d8609aae077701b596 /include/linux/nfs_xdr.h
parent9c93ab7dff5eb22027ab15010557bb73f9b44c99 (diff)
downloadop-kernel-dev-06cf6f2ed0b19629700794727d86ed57b9c0583e.zip
op-kernel-dev-06cf6f2ed0b19629700794727d86ed57b9c0583e.tar.gz
NFS: Eliminate nfs_get_user_pages()
Neil Brown observed that the kmalloc() in nfs_get_user_pages() is more likely to fail if the I/O is large enough to require the allocation of more than a single page to keep track of all the pinned pages in the user's buffer. Instead of tracking one large page array per dreq/iocb, track pages per nfs_read/write_data, just like the cached I/O path does. An array for pages is already allocated for us by nfs_readdata_alloc() (and the write and commit equivalents). This is also required for adding support for vectored I/O to the NFS direct I/O path. The original reason to pin the user buffer and allocate all the NFS data structures before trying to schedule I/O was to ensure all needed resources are allocated on the client before starting to send requests. This reduces the chance that resource exhaustion on the client will cause a short read or write. On the other hand, for an application making very large application I/O requests, this means that it will be nearly impossible for the application to make forward progress on a resource-limited client. Thus, moving the buffer pinning functionality into the I/O scheduling loops should be good for scalability. The next patch will do the same for NFS data structure allocation. Signed-off-by: Chuck Lever <cel@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Diffstat (limited to 'include/linux/nfs_xdr.h')
-rw-r--r--include/linux/nfs_xdr.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
index 7c7320f..2d3fb64 100644
--- a/include/linux/nfs_xdr.h
+++ b/include/linux/nfs_xdr.h
@@ -729,6 +729,7 @@ struct nfs_read_data {
struct list_head pages; /* Coalesced read requests */
struct nfs_page *req; /* multi ops per nfs_page */
struct page **pagevec;
+ unsigned int npages; /* active pages in pagevec */
struct nfs_readargs args;
struct nfs_readres res;
#ifdef CONFIG_NFS_V4
@@ -747,6 +748,7 @@ struct nfs_write_data {
struct list_head pages; /* Coalesced requests we wish to flush */
struct nfs_page *req; /* multi ops per nfs_page */
struct page **pagevec;
+ unsigned int npages; /* active pages in pagevec */
struct nfs_writeargs args; /* argument struct */
struct nfs_writeres res; /* result struct */
#ifdef CONFIG_NFS_V4
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