From: NeilBrown <neilb@suse.de>
To: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH 9/9] NFS: support LOOKUP_RCU in nfs_follow_link.
Date: Thu, 05 Mar 2015 16:21:21 +1100 [thread overview]
Message-ID: <20150305052121.23906.19303.stgit@notabene.brown> (raw)
In-Reply-To: <20150305051530.23906.65097.stgit@notabene.brown>
If the inode is valid and the page has been read in,
then we can follow a link in RCU-walk.
Signed-off-by: NeilBrown <neilb@suse.de>
---
fs/nfs/inode.c | 22 ++++++++++++++++++++++
fs/nfs/symlink.c | 19 +++++++++++++++++--
include/linux/nfs_fs.h | 1 +
3 files changed, 40 insertions(+), 2 deletions(-)
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index 83107be3dd01..80f192405102 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -1123,6 +1123,28 @@ out:
return ret;
}
+int nfs_revalidate_mapping_rcu(struct inode *inode)
+{
+ struct nfs_inode *nfsi = NFS_I(inode);
+ unsigned long *bitlock = &nfsi->flags;
+ int ret = 0;
+
+ if (IS_SWAPFILE(inode))
+ goto out;
+ if (nfs_mapping_need_revalidate_inode(inode)) {
+ ret = -ECHILD;
+ goto out;
+ }
+ spin_lock(&inode->i_lock);
+ if (test_bit(NFS_INO_INVALIDATING, bitlock) ||
+ (nfsi->cache_validity & NFS_INO_INVALID_DATA))
+ ret = -ECHILD;
+ spin_unlock(&inode->i_lock);
+out:
+ return ret;
+}
+
+
static unsigned long nfs_wcc_update_inode(struct inode *inode, struct nfs_fattr *fattr)
{
struct nfs_inode *nfsi = NFS_I(inode);
diff --git a/fs/nfs/symlink.c b/fs/nfs/symlink.c
index c9a2d3cc4619..3cd295b7e094 100644
--- a/fs/nfs/symlink.c
+++ b/fs/nfs/symlink.c
@@ -49,8 +49,23 @@ static void *nfs_follow_link(struct dentry *dentry, struct nameidata *nd)
struct page *page;
void *err;
- if (nd_is_rcu(nd))
- return ERR_PTR(-ECHILD);
+ if (nd_is_rcu(nd)) {
+ err = ERR_PTR(nfs_revalidate_mapping_rcu(inode));
+ if (err)
+ goto read_failed;
+ page = find_get_page(inode->i_mapping, 0);
+ if (page &&
+ (!PageUptodate(page) || PageHighMem(page))) {
+ put_page(page);
+ page = NULL;
+ }
+ if (!page) {
+ err = ERR_PTR(-ECHILD);
+ goto read_failed;
+ }
+ nd_set_link(nd, page_address(page));
+ return page;
+ }
err = ERR_PTR(nfs_revalidate_mapping(inode, inode->i_mapping));
if (err)
goto read_failed;
diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index 2f77e0c651c8..78c2f812eaeb 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -355,6 +355,7 @@ extern int nfs_revalidate_inode(struct nfs_server *server, struct inode *inode);
extern int nfs_revalidate_inode_rcu(struct nfs_server *server, struct inode *inode);
extern int __nfs_revalidate_inode(struct nfs_server *, struct inode *);
extern int nfs_revalidate_mapping(struct inode *inode, struct address_space *mapping);
+extern int nfs_revalidate_mapping_rcu(struct inode *inode);
extern int nfs_setattr(struct dentry *, struct iattr *);
extern void nfs_setattr_update_inode(struct inode *inode, struct iattr *attr);
extern void nfs_setsecurity(struct inode *inode, struct nfs_fattr *fattr,
next prev parent reply other threads:[~2015-03-05 5:21 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-05 5:21 [PATCH 0/9] Support follow_link in RCU-walk NeilBrown
2015-03-05 5:21 ` NeilBrown [this message]
2015-03-05 5:21 ` [PATCH 2/9] VFS/namei: use terminate_walk when symlink lookup fails NeilBrown
2015-03-05 5:21 ` [PATCH 6/9] VFS/namei: enable RCU-walk when following symlinks NeilBrown
2015-03-05 5:21 ` [PATCH 1/9] FS: make all ->follow_link handlers aware for LOOKUP_RCU NeilBrown
2015-03-05 5:21 ` [PATCH 5/9] VFS/namei: enhance follow_link to support RCU-walk NeilBrown
2015-03-05 5:21 ` [PATCH 3/9] VFS/namei: new flag to support RCU symlinks: LOOKUP_LINK_RCU NeilBrown
2015-03-05 5:21 ` [PATCH 4/9] VFS/namei: abort RCU-walk on symlink if atime needs updating NeilBrown
2015-03-05 5:21 ` [PATCH 7/9] VFS/namei: handle LOOKUP_RCU in page_follow_link_light NeilBrown
2015-03-05 5:21 ` [PATCH 8/9] XFS: allow follow_link to often succeed in RCU-walk NeilBrown
2015-03-05 6:05 ` [PATCH 0/9] Support follow_link " Al Viro
2015-03-05 13:52 ` John Stoffel
2015-03-05 16:00 ` Al Viro
2015-03-05 17:17 ` John Stoffel
2015-03-05 21:08 ` NeilBrown
2015-03-09 2:21 ` NeilBrown
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