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Subject[PATCH v2 11/11] teach nfs_get_link() to work in RCU mode
Date
From: Al Viro <viro@zeniv.linux.org.uk>

based upon the corresponding patch from Neil's March patchset,
again with kmap-related horrors removed.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
fs/nfs/inode.c | 21 +++++++++++++++++++++
fs/nfs/symlink.c | 30 ++++++++++++++++++++----------
include/linux/nfs_fs.h | 1 +
3 files changed, 42 insertions(+), 10 deletions(-)

diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index ae9aa0b..aa828e8 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -1087,6 +1087,27 @@ static bool nfs_mapping_need_revalidate_inode(struct inode *inode)
|| NFS_STALE(inode);
}

+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;
+}
+
/**
* __nfs_revalidate_mapping - Revalidate the pagecache
* @inode - pointer to host inode
diff --git a/fs/nfs/symlink.c b/fs/nfs/symlink.c
index 8ade8a8..95c69af 100644
--- a/fs/nfs/symlink.c
+++ b/fs/nfs/symlink.c
@@ -48,16 +48,26 @@ static const char *nfs_get_link(struct dentry *dentry,
struct page *page;
void *err;

- if (!dentry)
- return ERR_PTR(-ECHILD);
-
- err = ERR_PTR(nfs_revalidate_mapping(inode, inode->i_mapping));
- if (err)
- return err;
- page = read_cache_page(&inode->i_data, 0,
- (filler_t *)nfs_symlink_filler, inode);
- if (IS_ERR(page))
- return ERR_CAST(page);
+ if (!dentry) {
+ err = ERR_PTR(nfs_revalidate_mapping_rcu(inode));
+ if (err)
+ return err;
+ page = find_get_page(inode->i_mapping, 0);
+ if (!page)
+ return ERR_PTR(-ECHILD);
+ if (!PageUptodate(page)) {
+ put_page(page);
+ return ERR_PTR(-ECHILD);
+ }
+ } else {
+ err = ERR_PTR(nfs_revalidate_mapping(inode, inode->i_mapping));
+ if (err)
+ return err;
+ page = read_cache_page(&inode->i_data, 0,
+ (filler_t *)nfs_symlink_filler, inode);
+ if (IS_ERR(page))
+ return ERR_CAST(page);
+ }
*cookie = page;
return page_address(page);
}
diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h
index c0e9614..37a3d29 100644
--- a/include/linux/nfs_fs.h
+++ b/include/linux/nfs_fs.h
@@ -359,6 +359,7 @@ 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_revalidate_mapping_protected(struct inode *inode, struct address_space *mapping);
extern int nfs_setattr(struct dentry *, struct iattr *);
extern void nfs_setattr_update_inode(struct inode *inode, struct iattr *attr, struct nfs_fattr *);
--
2.1.4


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