165 lines
4.7 KiB
Diff
165 lines
4.7 KiB
Diff
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
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Subject: [PATCH 26/31] nfs: disable data cache revalidation for swapfiles
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Patch-mainline: Not yet
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Do as Trond suggested:
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http://lkml.org/lkml/2006/8/25/348
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Disable NFS data cache revalidation on swap files since it doesn't really
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make sense to have other clients change the file while you are using it.
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Thereby we can stop setting PG_private on swap pages, since there ought to
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be no further races with invalidate_inode_pages2() to deal with.
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And since we cannot set PG_private we cannot use page->private (which is
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already used by PG_swapcache pages anyway) to store the nfs_page. Thus
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augment the new nfs_page_find_request logic.
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Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
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Signed-off-by: Suresh Jayaraman <sjayaraman@suse.de>
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---
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fs/nfs/inode.c | 6 ++++
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fs/nfs/write.c | 75 ++++++++++++++++++++++++++++++++++++++++++++++-----------
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2 files changed, 67 insertions(+), 14 deletions(-)
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--- a/fs/nfs/inode.c
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+++ b/fs/nfs/inode.c
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@@ -868,6 +868,12 @@ int nfs_revalidate_mapping(struct inode
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struct nfs_inode *nfsi = NFS_I(inode);
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int ret = 0;
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+ /*
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+ * swapfiles are not supposed to be shared.
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+ */
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+ if (IS_SWAPFILE(inode))
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+ goto out;
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+
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if ((nfsi->cache_validity & NFS_INO_REVAL_PAGECACHE)
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|| nfs_attribute_cache_expired(inode)
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|| NFS_STALE(inode)) {
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--- a/fs/nfs/write.c
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+++ b/fs/nfs/write.c
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@@ -107,25 +107,64 @@ static void nfs_context_set_write_error(
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set_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags);
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}
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-static struct nfs_page *nfs_page_find_request_locked(struct page *page)
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+static struct nfs_page *
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+__nfs_page_find_request_locked(struct nfs_inode *nfsi, struct page *page,
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+ int get)
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{
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struct nfs_page *req = NULL;
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- if (PagePrivate(page)) {
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+ if (PagePrivate(page))
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req = (struct nfs_page *)page_private(page);
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- if (req != NULL)
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- kref_get(&req->wb_kref);
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- }
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+ else if (unlikely(PageSwapCache(page)))
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+ req = radix_tree_lookup(&nfsi->nfs_page_tree,
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+ page_file_index(page));
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+
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+ if (get && req)
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+ kref_get(&req->wb_kref);
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+
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return req;
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}
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+static inline struct nfs_page *
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+nfs_page_find_request_locked(struct nfs_inode *nfsi, struct page *page)
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+{
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+ return __nfs_page_find_request_locked(nfsi, page, 1);
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+}
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+
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+static int __nfs_page_has_request(struct page *page)
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+{
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+ struct inode *inode = page_file_mapping(page)->host;
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+ struct nfs_page *req = NULL;
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+
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+ spin_lock(&inode->i_lock);
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+ req = __nfs_page_find_request_locked(NFS_I(inode), page, 0);
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+ spin_unlock(&inode->i_lock);
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+
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+ /*
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+ * hole here plugged by the caller holding onto PG_locked
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+ */
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+
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+ return req != NULL;
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+}
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+
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+static inline int nfs_page_has_request(struct page *page)
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+{
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+ if (PagePrivate(page))
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+ return 1;
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+
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+ if (unlikely(PageSwapCache(page)))
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+ return __nfs_page_has_request(page);
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+
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+ return 0;
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+}
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+
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static struct nfs_page *nfs_page_find_request(struct page *page)
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{
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struct inode *inode = page_file_mapping(page)->host;
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struct nfs_page *req = NULL;
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spin_lock(&inode->i_lock);
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- req = nfs_page_find_request_locked(page);
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+ req = nfs_page_find_request_locked(NFS_I(inode), page);
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spin_unlock(&inode->i_lock);
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return req;
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}
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@@ -228,7 +267,7 @@ static struct nfs_page *nfs_find_and_loc
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spin_lock(&inode->i_lock);
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for (;;) {
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- req = nfs_page_find_request_locked(page);
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+ req = nfs_page_find_request_locked(NFS_I(inode), page);
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if (req == NULL)
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break;
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if (nfs_set_page_tag_locked(req))
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@@ -391,9 +430,15 @@ static int nfs_inode_add_request(struct
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if (nfs_have_delegation(inode, FMODE_WRITE))
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nfsi->change_attr++;
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}
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- set_bit(PG_MAPPED, &req->wb_flags);
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- SetPagePrivate(req->wb_page);
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- set_page_private(req->wb_page, (unsigned long)req);
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+ /*
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+ * Swap-space should not get truncated. Hence no need to plug the race
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+ * with invalidate/truncate.
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+ */
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+ if (likely(!PageSwapCache(req->wb_page))) {
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+ set_bit(PG_MAPPED, &req->wb_flags);
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+ SetPagePrivate(req->wb_page);
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+ set_page_private(req->wb_page, (unsigned long)req);
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+ }
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nfsi->npages++;
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kref_get(&req->wb_kref);
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radix_tree_tag_set(&nfsi->nfs_page_tree, req->wb_index,
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@@ -415,9 +460,11 @@ static void nfs_inode_remove_request(str
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BUG_ON (!NFS_WBACK_BUSY(req));
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spin_lock(&inode->i_lock);
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- set_page_private(req->wb_page, 0);
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- ClearPagePrivate(req->wb_page);
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- clear_bit(PG_MAPPED, &req->wb_flags);
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+ if (likely(!PageSwapCache(req->wb_page))) {
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+ set_page_private(req->wb_page, 0);
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+ ClearPagePrivate(req->wb_page);
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+ clear_bit(PG_MAPPED, &req->wb_flags);
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+ }
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radix_tree_delete(&nfsi->nfs_page_tree, req->wb_index);
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nfsi->npages--;
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if (!nfsi->npages) {
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@@ -585,7 +632,7 @@ static struct nfs_page *nfs_try_to_updat
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spin_lock(&inode->i_lock);
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for (;;) {
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- req = nfs_page_find_request_locked(page);
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+ req = nfs_page_find_request_locked(NFS_I(inode), page);
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if (req == NULL)
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goto out_unlock;
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