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authorJeff Layton <jlayton@redhat.com>2014-01-28 19:47:46 +0100
committerTrond Myklebust <trond.myklebust@primarydata.com>2014-01-28 20:48:18 +0100
commit4db72b40fdbc706f8957e9773ae73b1574b8c694 (patch)
tree7ccf6324c0643b0b35c1ccc0895292f51000685e /fs/nfs
parentNFS: Fix races in nfs_revalidate_mapping (diff)
downloadlinux-4db72b40fdbc706f8957e9773ae73b1574b8c694.tar.xz
linux-4db72b40fdbc706f8957e9773ae73b1574b8c694.zip
nfs: add memory barriers around NFS_INO_INVALID_DATA and NFS_INO_INVALIDATING
If the setting of NFS_INO_INVALIDATING gets reordered to before the clearing of NFS_INO_INVALID_DATA, then another task may hit a race window where both appear to be clear, even though the inode's pages are still in need of invalidation. Fix this by adding the appropriate memory barriers. Signed-off-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Diffstat (limited to 'fs/nfs')
-rw-r--r--fs/nfs/dir.c14
-rw-r--r--fs/nfs/inode.c1
-rw-r--r--fs/nfs/write.c1
3 files changed, 13 insertions, 3 deletions
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index b39a0468829b..be38b573495a 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -274,6 +274,15 @@ out_eof:
return -EBADCOOKIE;
}
+static bool
+nfs_readdir_inode_mapping_valid(struct nfs_inode *nfsi)
+{
+ if (nfsi->cache_validity & (NFS_INO_INVALID_ATTR|NFS_INO_INVALID_DATA))
+ return false;
+ smp_rmb();
+ return !test_bit(NFS_INO_INVALIDATING, &nfsi->flags);
+}
+
static
int nfs_readdir_search_for_cookie(struct nfs_cache_array *array, nfs_readdir_descriptor_t *desc)
{
@@ -287,9 +296,8 @@ int nfs_readdir_search_for_cookie(struct nfs_cache_array *array, nfs_readdir_des
struct nfs_open_dir_context *ctx = desc->file->private_data;
new_pos = desc->current_index + i;
- if (ctx->attr_gencount != nfsi->attr_gencount
- || (nfsi->cache_validity & (NFS_INO_INVALID_ATTR|NFS_INO_INVALID_DATA))
- || test_bit(NFS_INO_INVALIDATING, &nfsi->flags)) {
+ if (ctx->attr_gencount != nfsi->attr_gencount ||
+ !nfs_readdir_inode_mapping_valid(nfsi)) {
ctx->duped = 0;
ctx->attr_gencount = nfsi->attr_gencount;
} else if (new_pos < desc->ctx->pos) {
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index e5070aa5f175..02e185168602 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -1050,6 +1050,7 @@ int nfs_revalidate_mapping(struct inode *inode, struct address_space *mapping)
}
set_bit(NFS_INO_INVALIDATING, bitlock);
+ smp_wmb();
nfsi->cache_validity &= ~NFS_INO_INVALID_DATA;
spin_unlock(&inode->i_lock);
trace_nfs_invalidate_mapping_enter(inode);
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 5511a4247190..9a3b6a4cd6b9 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -915,6 +915,7 @@ static bool nfs_write_pageuptodate(struct page *page, struct inode *inode)
goto out;
if (nfsi->cache_validity & (NFS_INO_INVALID_DATA|NFS_INO_REVAL_PAGECACHE))
return false;
+ smp_rmb();
if (test_bit(NFS_INO_INVALIDATING, &nfsi->flags))
return false;
out: