NFS: copy symlinks into page cache before sending NFS SYMLINK request (873101b3) · Commits · 戴 / test

fs/nfs/dir.c

+68 −18

Original line number	Diff line number	Diff line
		@@ -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>

		@@ -1441,41 +1442,90 @@ 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 0;
		}

		static int
		nfs_link(struct dentry old_dentry, struct inode dir, struct dentry *dentry)
		{

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