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Subject[PATCH v2 2/3] NFS: lock the readdir page while it is in use
Date
Before we can fix the memory leak due to not freeing up the contents
of the nfs_cache_array when clearing the page cache, we need to
ensure that shrink_page_list can't just lock the page and
call try_to_release_page() while we're accessing the array.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
---
fs/nfs/dir.c | 16 +++++++++++++++-
1 files changed, 15 insertions(+), 1 deletions(-)

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index e03537f..3ec3f1c 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -639,6 +639,7 @@ int nfs_readdir_filler(nfs_readdir_descriptor_t *desc, struct page* page)
static
void cache_page_release(nfs_readdir_descriptor_t *desc)
{
+ unlock_page(desc->page);
page_cache_release(desc->page);
desc->page = NULL;
}
@@ -646,8 +647,20 @@ void cache_page_release(nfs_readdir_descriptor_t *desc)
static
struct page *get_cache_page(nfs_readdir_descriptor_t *desc)
{
- return read_cache_page(desc->file->f_path.dentry->d_inode->i_mapping,
+ struct page *page;
+
+ for (;;) {
+ page = read_cache_page(desc->file->f_path.dentry->d_inode->i_mapping,
desc->page_index, (filler_t *)nfs_readdir_filler, desc);
+ if (IS_ERR(page))
+ break;
+ lock_page(page);
+ if (page->mapping != NULL && PageUptodate(page))
+ break;
+ unlock_page(page);
+ page_cache_release(page);
+ }
+ return page;
}

/*
@@ -771,6 +784,7 @@ int uncached_readdir(nfs_readdir_descriptor_t *desc, void *dirent,
desc->page_index = 0;
desc->last_cookie = *desc->dir_cookie;
desc->page = page;
+ lock_page(page);

status = nfs_readdir_xdr_to_array(desc, page, inode);
if (status < 0)
--
1.7.3.2


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