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author | Trond Myklebust <trondmy@gmail.com> | 2020-02-02 17:53:54 -0500 |
---|---|---|
committer | Ben Hutchings <ben@decadent.org.uk> | 2020-05-22 21:19:43 +0100 |
commit | 4a6b1c75bceade9ece26918bb448d42b15afd29b (patch) | |
tree | 6006af66305e6e2a3be6bcea0be741e783364a78 | |
parent | b2b6bbf8c801fa2f9756b095e10c232418f7cddd (diff) | |
download | linux-stable-4a6b1c75bceade9ece26918bb448d42b15afd29b.tar.gz |
NFS: Directory page cache pages need to be locked when read
commit 114de38225d9b300f027e2aec9afbb6e0def154b upstream.
When a NFS directory page cache page is removed from the page cache,
its contents are freed through a call to nfs_readdir_clear_array().
To prevent the removal of the page cache entry until after we've
finished reading it, we must take the page lock.
Fixes: 11de3b11e08c ("NFS: Fix a memory leak in nfs_readdir")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Reviewed-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
-rw-r--r-- | fs/nfs/dir.c | 30 |
1 files changed, 19 insertions, 11 deletions
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c index 6458364eff1e5..94215aac71558 100644 --- a/fs/nfs/dir.c +++ b/fs/nfs/dir.c @@ -671,8 +671,6 @@ int nfs_readdir_filler(nfs_readdir_descriptor_t *desc, struct page* page) static void cache_page_release(nfs_readdir_descriptor_t *desc) { - if (!desc->page->mapping) - nfs_readdir_clear_array(desc->page); page_cache_release(desc->page); desc->page = NULL; } @@ -686,19 +684,28 @@ struct page *get_cache_page(nfs_readdir_descriptor_t *desc) /* * Returns 0 if desc->dir_cookie was found on page desc->page_index + * and locks the page to prevent removal from the page cache. */ static -int find_cache_page(nfs_readdir_descriptor_t *desc) +int find_and_lock_cache_page(nfs_readdir_descriptor_t *desc) { int res; desc->page = get_cache_page(desc); if (IS_ERR(desc->page)) return PTR_ERR(desc->page); - - res = nfs_readdir_search_array(desc); + res = lock_page_killable(desc->page); if (res != 0) - cache_page_release(desc); + goto error; + res = -EAGAIN; + if (desc->page->mapping != NULL) { + res = nfs_readdir_search_array(desc); + if (res == 0) + return 0; + } + unlock_page(desc->page); +error: + cache_page_release(desc); return res; } @@ -713,7 +720,7 @@ int readdir_search_pagecache(nfs_readdir_descriptor_t *desc) desc->last_cookie = 0; } do { - res = find_cache_page(desc); + res = find_and_lock_cache_page(desc); } while (res == -EAGAIN); return res; } @@ -752,7 +759,6 @@ int nfs_do_filldir(nfs_readdir_descriptor_t *desc) desc->eof = 1; kunmap(desc->page); - cache_page_release(desc); dfprintk(DIRCACHE, "NFS: nfs_do_filldir() filling ended @ cookie %Lu; returning = %d\n", (unsigned long long)*desc->dir_cookie, res); return res; @@ -798,13 +804,13 @@ int uncached_readdir(nfs_readdir_descriptor_t *desc) status = nfs_do_filldir(desc); + out_release: + nfs_readdir_clear_array(desc->page); + cache_page_release(desc); out: dfprintk(DIRCACHE, "NFS: %s: returns %d\n", __func__, status); return status; - out_release: - cache_page_release(desc); - goto out; } /* The file offset position represents the dirent entry number. A @@ -870,6 +876,8 @@ static int nfs_readdir(struct file *file, struct dir_context *ctx) break; res = nfs_do_filldir(desc); + unlock_page(desc->page); + cache_page_release(desc); if (res < 0) break; } while (!desc->eof); |