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teach nfs_get_link() to work in RCU mode 

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>
This commit is contained in:
Al Viro 2015-11-17 21:14:24 -05:00
parent 1a384eaac2
commit 0d0def49d0
3 changed files with 42 additions and 10 deletions
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21
fs/nfs/inode.c
View File

@ -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

30
fs/nfs/symlink.c
View File

@ -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);
}

1
include/linux/nfs_fs.h
View File

@ -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 *);