From: Trond Myklebust <trondmy@gmail.com>
To: Anna Schumaker <Anna.Schumaker@netapp.com>
Cc: Benjamin Coddington <bcodding@redhat.com>,
Dai Ngo <dai.ngo@oracle.com>,
linux-nfs@vger.kernel.org
Subject: [PATCH 2/4] NFS: Directory page cache pages need to be locked when read
Date: Sun, 2 Feb 2020 17:53:54 -0500 [thread overview]
Message-ID: <20200202225356.995080-3-trond.myklebust@hammerspace.com> (raw)
In-Reply-To: <20200202225356.995080-2-trond.myklebust@hammerspace.com>
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")
Cc: stable@vger.kernel.org # v2.6.37+
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
---
fs/nfs/dir.c | 30 +++++++++++++++++++-----------
1 file changed, 19 insertions(+), 11 deletions(-)
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index ba0d55930e8a..90467b44ec13 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -705,8 +705,6 @@ int nfs_readdir_filler(void *data, struct page* page)
static
void cache_page_release(nfs_readdir_descriptor_t *desc)
{
- if (!desc->page->mapping)
- nfs_readdir_clear_array(desc->page);
put_page(desc->page);
desc->page = NULL;
}
@@ -720,19 +718,28 @@ 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;
}
@@ -747,7 +754,7 @@ 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;
}
@@ -786,7 +793,6 @@ int nfs_do_filldir(nfs_readdir_descriptor_t *desc)
desc->eof = true;
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;
@@ -832,13 +838,13 @@ 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
@@ -903,6 +909,8 @@ 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);
--
2.24.1
next prev parent reply other threads:[~2020-02-02 22:56 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-02 22:53 [PATCH 0/4] Readdir fixes Trond Myklebust
2020-02-02 22:53 ` [PATCH 1/4] NFS: Fix memory leaks and corruption in readdir Trond Myklebust
2020-02-02 22:53 ` Trond Myklebust [this message]
2020-02-02 22:53 ` [PATCH 3/4] NFS: Use kmemdup_nul() in nfs_readdir_make_qstr() Trond Myklebust
2020-02-02 22:53 ` [PATCH 4/4] NFS: Switch readdir to using iterate_shared() Trond Myklebust
2020-02-03 14:41 ` Benjamin Coddington
2020-02-03 14:22 ` [PATCH 3/4] NFS: Use kmemdup_nul() in nfs_readdir_make_qstr() Benjamin Coddington
2020-02-03 14:21 ` [PATCH 2/4] NFS: Directory page cache pages need to be locked when read Benjamin Coddington
2020-02-03 20:31 ` Schumaker, Anna
2020-02-03 21:18 ` Trond Myklebust
2020-02-03 21:21 ` Schumaker, Anna
2020-02-03 22:45 ` Trond Myklebust
2020-02-03 22:50 ` Trond Myklebust
2020-02-03 22:55 ` Trond Myklebust
2020-02-05 0:44 ` Dai Ngo
2020-02-03 13:44 ` [PATCH 1/4] NFS: Fix memory leaks and corruption in readdir Benjamin Coddington
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