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NFS: Reduce number of RPC calls when doing uncached readdir

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If we're doing uncached readdir, allocate multiple pages in order to
try to avoid duplicate RPC calls for the same getdents() call.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Reviewed-by: Benjamin Coddington <bcodding@redhat.com>
Tested-by: Benjamin Coddington <bcodding@redhat.com>
Tested-by: Dave Wysochanski <dwysocha@redhat.com>
This commit is contained in:
Trond Myklebust 2020-11-06 20:38:47 -05:00
parent 762567b7c7
commit 35df59d3ef
1 changed files with 69 additions and 36 deletions
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105
fs/nfs/dir.c
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@ -199,6 +199,23 @@ void nfs_readdir_clear_array(struct page *page)
kunmap_atomic(array);
}
static struct page *
nfs_readdir_page_array_alloc(u64 last_cookie, gfp_t gfp_flags)
{
struct page *page = alloc_page(gfp_flags);
if (page)
nfs_readdir_page_init_array(page, last_cookie);
return page;
}
static void nfs_readdir_page_array_free(struct page *page)
{
if (page) {
nfs_readdir_clear_array(page);
put_page(page);
}
}
static void nfs_readdir_array_set_eof(struct nfs_cache_array *array)
{
array->page_is_eof = 1;
@ -694,12 +711,14 @@ out:
static int nfs_readdir_page_filler(struct nfs_readdir_descriptor *desc,
struct nfs_entry *entry,
struct page **xdr_pages,
struct page *fillme, unsigned int buflen)
unsigned int buflen,
struct page **arrays,
size_t narrays)
{
struct address_space *mapping = desc->file->f_mapping;
struct xdr_stream stream;
struct xdr_buf buf;
struct page *scratch, *new, *page = fillme;
struct page *scratch, *new, *page = *arrays;
int status;
scratch = alloc_page(GFP_KERNEL);
@ -725,15 +744,25 @@ static int nfs_readdir_page_filler(struct nfs_readdir_descriptor *desc,
if (status != -ENOSPC)
continue;
if (page->mapping != mapping)
break;
new = nfs_readdir_page_get_next(mapping, page->index + 1,
entry->prev_cookie);
if (!new)
break;
if (page != fillme)
nfs_readdir_page_unlock_and_put(page);
page = new;
if (page->mapping != mapping) {
if (!--narrays)
break;
new = nfs_readdir_page_array_alloc(entry->prev_cookie,
GFP_KERNEL);
if (!new)
break;
arrays++;
*arrays = page = new;
} else {
new = nfs_readdir_page_get_next(mapping,
page->index + 1,
entry->prev_cookie);
if (!new)
break;
if (page != *arrays)
nfs_readdir_page_unlock_and_put(page);
page = new;
}
status = nfs_readdir_add_to_array(entry, page);
} while (!status && !entry->eof);
@ -750,7 +779,7 @@ static int nfs_readdir_page_filler(struct nfs_readdir_descriptor *desc,
break;
}
if (page != fillme)
if (page != *arrays)
nfs_readdir_page_unlock_and_put(page);
put_page(scratch);
@ -790,10 +819,11 @@ out_freepages:
}
static int nfs_readdir_xdr_to_array(struct nfs_readdir_descriptor *desc,
struct page *page, __be32 *verf_arg,
__be32 *verf_res)
__be32 *verf_arg, __be32 *verf_res,
struct page **arrays, size_t narrays)
{
struct page **pages;
struct page *page = *arrays;
struct nfs_entry *entry;
size_t array_size;
struct inode *inode = file_inode(desc->file);
@ -835,7 +865,8 @@ static int nfs_readdir_xdr_to_array(struct nfs_readdir_descriptor *desc,
break;
}
status = nfs_readdir_page_filler(desc, entry, pages, page, pglen);
status = nfs_readdir_page_filler(desc, entry, pages, pglen,
arrays, narrays);
} while (!status && nfs_readdir_page_needs_filling(page));
nfs_readdir_free_pages(pages, array_size);
@ -884,8 +915,8 @@ static int find_and_lock_cache_page(struct nfs_readdir_descriptor *desc)
if (!desc->page)
return -ENOMEM;
if (nfs_readdir_page_needs_filling(desc->page)) {
res = nfs_readdir_xdr_to_array(desc, desc->page,
nfsi->cookieverf, verf);
res = nfs_readdir_xdr_to_array(desc, nfsi->cookieverf, verf,
&desc->page, 1);
if (res < 0) {
nfs_readdir_page_unlock_and_put_cached(desc);
if (res == -EBADCOOKIE || res == -ENOTSYNC) {
@ -976,37 +1007,39 @@ static void nfs_do_filldir(struct nfs_readdir_descriptor *desc)
*/
static int uncached_readdir(struct nfs_readdir_descriptor *desc)
{
struct page *page = NULL;
struct page **arrays;
size_t i, sz = 512;
__be32 verf[NFS_DIR_VERIFIER_SIZE];
int status;
int status = -ENOMEM;
dfprintk(DIRCACHE, "NFS: uncached_readdir() searching for cookie %Lu\n",
dfprintk(DIRCACHE, "NFS: uncached_readdir() searching for cookie %llu\n",
(unsigned long long)desc->dir_cookie);
page = alloc_page(GFP_HIGHUSER);
if (!page) {
status = -ENOMEM;
arrays = kcalloc(sz, sizeof(*arrays), GFP_KERNEL);
if (!arrays)
goto out;
arrays[0] = nfs_readdir_page_array_alloc(desc->dir_cookie, GFP_KERNEL);
if (!arrays[0])
goto out;
}
desc->page_index = 0;
desc->last_cookie = desc->dir_cookie;
desc->page = page;
desc->duped = 0;
nfs_readdir_page_init_array(page, desc->dir_cookie);
status = nfs_readdir_xdr_to_array(desc, page, desc->verf, verf);
if (status < 0)
goto out_release;
status = nfs_readdir_xdr_to_array(desc, desc->verf, verf, arrays, sz);
nfs_do_filldir(desc);
for (i = 0; !desc->eof && i < sz && arrays[i]; i++) {
desc->page = arrays[i];
nfs_do_filldir(desc);
}
desc->page = NULL;
out_release:
nfs_readdir_clear_array(desc->page);
nfs_readdir_page_put(desc);
out:
dfprintk(DIRCACHE, "NFS: %s: returns %d\n",
__func__, status);
for (i = 0; i < sz && arrays[i]; i++)
nfs_readdir_page_array_free(arrays[i]);
out:
kfree(arrays);
dfprintk(DIRCACHE, "NFS: %s: returns %d\n", __func__, status);
return status;
}