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-rw-r--r--fs/nfs/dir.c86
1 files changed, 68 insertions, 18 deletions
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index affd3ae..b483e5d 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -30,6 +30,7 @@
#include <linux/nfs_mount.h>
#include <linux/pagemap.h>
#include <linux/smp_lock.h>
+#include <linux/pagevec.h>
#include <linux/namei.h>
#include <linux/mount.h>
@@ -1441,39 +1442,88 @@ static int nfs_unlink(struct inode *dir, struct dentry *dentry)
return error;
}
-static int
-nfs_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
+/*
+ * To create a symbolic link, most file systems instantiate a new inode,
+ * add a page to it containing the path, then write it out to the disk
+ * using prepare_write/commit_write.
+ *
+ * Unfortunately the NFS client can't create the in-core inode first
+ * because it needs a file handle to create an in-core inode (see
+ * fs/nfs/inode.c:nfs_fhget). We only have a file handle *after* the
+ * symlink request has completed on the server.
+ *
+ * So instead we allocate a raw page, copy the symname into it, then do
+ * the SYMLINK request with the page as the buffer. If it succeeds, we
+ * now have a new file handle and can instantiate an in-core NFS inode
+ * and move the raw page into its mapping.
+ */
+static int nfs_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
{
+ struct pagevec lru_pvec;
+ struct page *page;
+ char *kaddr;
struct iattr attr;
- struct qstr qsymname;
+ unsigned int pathlen = strlen(symname);
+ struct qstr qsymname = {
+ .name = symname,
+ .len = pathlen,
+ };
int error;
dfprintk(VFS, "NFS: symlink(%s/%ld, %s, %s)\n", dir->i_sb->s_id,
dir->i_ino, dentry->d_name.name, symname);
-#ifdef NFS_PARANOIA
-if (dentry->d_inode)
-printk("nfs_proc_symlink: %s/%s not negative!\n",
-dentry->d_parent->d_name.name, dentry->d_name.name);
-#endif
- /*
- * Fill in the sattr for the call.
- * Note: SunOS 4.1.2 crashes if the mode isn't initialized!
- */
- attr.ia_valid = ATTR_MODE;
- attr.ia_mode = S_IFLNK | S_IRWXUGO;
+ if (pathlen > PAGE_SIZE)
+ return -ENAMETOOLONG;
- qsymname.name = symname;
- qsymname.len = strlen(symname);
+ attr.ia_mode = S_IFLNK | S_IRWXUGO;
+ attr.ia_valid = ATTR_MODE;
lock_kernel();
+
+ page = alloc_page(GFP_KERNEL);
+ if (!page) {
+ unlock_kernel();
+ return -ENOMEM;
+ }
+
+ kaddr = kmap_atomic(page, KM_USER0);
+ memcpy(kaddr, symname, pathlen);
+ if (pathlen < PAGE_SIZE)
+ memset(kaddr + pathlen, 0, PAGE_SIZE - pathlen);
+ kunmap_atomic(kaddr, KM_USER0);
+
+ /* XXX: eventually this will pass in {page, pathlen},
+ * instead of qsymname; need XDR changes for that */
nfs_begin_data_update(dir);
error = NFS_PROTO(dir)->symlink(dir, dentry, &qsymname, &attr);
nfs_end_data_update(dir);
- if (!error)
+ if (error != 0) {
+ dfprintk(VFS, "NFS: symlink(%s/%ld, %s, %s) error %d\n",
+ dir->i_sb->s_id, dir->i_ino,
+ dentry->d_name.name, symname, error);
d_drop(dentry);
+ __free_page(page);
+ unlock_kernel();
+ return error;
+ }
+
+ /*
+ * No big deal if we can't add this page to the page cache here.
+ * READLINK will get the missing page from the server if needed.
+ */
+ pagevec_init(&lru_pvec, 0);
+ if (!add_to_page_cache(page, dentry->d_inode->i_mapping, 0,
+ GFP_KERNEL)) {
+ if (!pagevec_add(&lru_pvec, page))
+ __pagevec_lru_add(&lru_pvec);
+ SetPageUptodate(page);
+ unlock_page(page);
+ } else
+ __free_page(page);
+
unlock_kernel();
- return error;
+ return 0;
}
static int
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