[PATCH] NFS: Hide NFS server-generated readdir cookies from userland
NFSv3 currently returns the unsigned 64-bit cookie directly to userspace. The following patch causes the kernel to generate loff_t offsets for the benefit of userland. The current server-generated READDIR cookie is cached in the nfs_open_context instead of in filp->f_pos, so we still end up work correctly under directory insertions/deletion. Signed-off-by: Olivier Galibert <galibert@pobox.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
This commit is contained in:
Родитель
ae3884621b
Коммит
00a9264227
114
fs/nfs/dir.c
114
fs/nfs/dir.c
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@ -141,7 +141,9 @@ typedef struct {
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struct page *page;
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struct page *page;
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unsigned long page_index;
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unsigned long page_index;
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u32 *ptr;
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u32 *ptr;
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u64 target;
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u64 target_cookie;
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int target_index;
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int current_index;
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struct nfs_entry *entry;
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struct nfs_entry *entry;
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decode_dirent_t decode;
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decode_dirent_t decode;
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int plus;
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int plus;
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@ -225,14 +227,14 @@ void dir_page_release(nfs_readdir_descriptor_t *desc)
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/*
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/*
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* Given a pointer to a buffer that has already been filled by a call
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* Given a pointer to a buffer that has already been filled by a call
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* to readdir, find the next entry.
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* to readdir, find the next entry with cookie 'desc->target_cookie'.
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*
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*
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* If the end of the buffer has been reached, return -EAGAIN, if not,
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* If the end of the buffer has been reached, return -EAGAIN, if not,
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* return the offset within the buffer of the next entry to be
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* return the offset within the buffer of the next entry to be
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* read.
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* read.
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*/
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*/
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static inline
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static inline
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int find_dirent(nfs_readdir_descriptor_t *desc, struct page *page)
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int find_dirent(nfs_readdir_descriptor_t *desc)
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{
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{
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struct nfs_entry *entry = desc->entry;
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struct nfs_entry *entry = desc->entry;
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int loop_count = 0,
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int loop_count = 0,
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@ -240,7 +242,7 @@ int find_dirent(nfs_readdir_descriptor_t *desc, struct page *page)
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while((status = dir_decode(desc)) == 0) {
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while((status = dir_decode(desc)) == 0) {
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dfprintk(VFS, "NFS: found cookie %Lu\n", (long long)entry->cookie);
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dfprintk(VFS, "NFS: found cookie %Lu\n", (long long)entry->cookie);
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if (entry->prev_cookie == desc->target)
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if (entry->prev_cookie == desc->target_cookie)
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break;
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break;
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if (loop_count++ > 200) {
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if (loop_count++ > 200) {
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loop_count = 0;
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loop_count = 0;
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@ -252,8 +254,44 @@ int find_dirent(nfs_readdir_descriptor_t *desc, struct page *page)
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}
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}
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/*
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/*
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* Find the given page, and call find_dirent() in order to try to
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* Given a pointer to a buffer that has already been filled by a call
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* return the next entry.
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* to readdir, find the entry at offset 'desc->target_index'.
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*
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* If the end of the buffer has been reached, return -EAGAIN, if not,
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* return the offset within the buffer of the next entry to be
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* read.
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*/
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static inline
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int find_dirent_index(nfs_readdir_descriptor_t *desc)
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{
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struct nfs_entry *entry = desc->entry;
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int loop_count = 0,
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status;
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for(;;) {
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status = dir_decode(desc);
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if (status)
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break;
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dfprintk(VFS, "NFS: found cookie %Lu at index %d\n", (long long)entry->cookie, desc->current_index);
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if (desc->target_index == desc->current_index) {
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desc->target_cookie = entry->cookie;
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break;
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}
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desc->current_index++;
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if (loop_count++ > 200) {
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loop_count = 0;
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schedule();
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}
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}
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dfprintk(VFS, "NFS: find_dirent_index() returns %d\n", status);
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return status;
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}
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/*
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* Find the given page, and call find_dirent() or find_dirent_index in
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* order to try to return the next entry.
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*/
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*/
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static inline
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static inline
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int find_dirent_page(nfs_readdir_descriptor_t *desc)
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int find_dirent_page(nfs_readdir_descriptor_t *desc)
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@ -276,7 +314,10 @@ int find_dirent_page(nfs_readdir_descriptor_t *desc)
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/* NOTE: Someone else may have changed the READDIRPLUS flag */
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/* NOTE: Someone else may have changed the READDIRPLUS flag */
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desc->page = page;
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desc->page = page;
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desc->ptr = kmap(page); /* matching kunmap in nfs_do_filldir */
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desc->ptr = kmap(page); /* matching kunmap in nfs_do_filldir */
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status = find_dirent(desc, page);
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if (desc->target_cookie)
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status = find_dirent(desc);
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else
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status = find_dirent_index(desc);
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if (status < 0)
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if (status < 0)
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dir_page_release(desc);
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dir_page_release(desc);
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out:
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out:
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@ -291,7 +332,8 @@ int find_dirent_page(nfs_readdir_descriptor_t *desc)
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* Recurse through the page cache pages, and return a
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* Recurse through the page cache pages, and return a
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* filled nfs_entry structure of the next directory entry if possible.
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* filled nfs_entry structure of the next directory entry if possible.
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*
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*
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* The target for the search is 'desc->target'.
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* The target for the search is 'desc->target_cookie' if non-0,
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* 'desc->target_index' otherwise
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*/
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*/
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static inline
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static inline
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int readdir_search_pagecache(nfs_readdir_descriptor_t *desc)
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int readdir_search_pagecache(nfs_readdir_descriptor_t *desc)
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@ -299,7 +341,19 @@ int readdir_search_pagecache(nfs_readdir_descriptor_t *desc)
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int loop_count = 0;
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int loop_count = 0;
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int res;
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int res;
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dfprintk(VFS, "NFS: readdir_search_pagecache() searching for cookie %Lu\n", (long long)desc->target);
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if (desc->target_cookie)
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dfprintk(VFS, "NFS: readdir_search_pagecache() searching for cookie %Lu\n", (long long)desc->target_cookie);
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else
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dfprintk(VFS, "NFS: readdir_search_pagecache() searching for cookie number %d\n", desc->target_index);
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/* Always search-by-index from the beginning of the cache */
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if (!(desc->target_cookie)) {
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desc->page_index = 0;
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desc->entry->cookie = desc->entry->prev_cookie = 0;
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desc->entry->eof = 0;
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desc->current_index = 0;
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}
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for (;;) {
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for (;;) {
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res = find_dirent_page(desc);
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res = find_dirent_page(desc);
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if (res != -EAGAIN)
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if (res != -EAGAIN)
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@ -332,11 +386,12 @@ int nfs_do_filldir(nfs_readdir_descriptor_t *desc, void *dirent,
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struct file *file = desc->file;
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struct file *file = desc->file;
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struct nfs_entry *entry = desc->entry;
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struct nfs_entry *entry = desc->entry;
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struct dentry *dentry = NULL;
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struct dentry *dentry = NULL;
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struct nfs_open_context *ctx = file->private_data;
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unsigned long fileid;
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unsigned long fileid;
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int loop_count = 0,
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int loop_count = 0,
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res;
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res;
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dfprintk(VFS, "NFS: nfs_do_filldir() filling starting @ cookie %Lu\n", (long long)desc->target);
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dfprintk(VFS, "NFS: nfs_do_filldir() filling starting @ cookie %Lu\n", (long long)entry->cookie);
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for(;;) {
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for(;;) {
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unsigned d_type = DT_UNKNOWN;
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unsigned d_type = DT_UNKNOWN;
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@ -356,10 +411,11 @@ int nfs_do_filldir(nfs_readdir_descriptor_t *desc, void *dirent,
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}
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}
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res = filldir(dirent, entry->name, entry->len,
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res = filldir(dirent, entry->name, entry->len,
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entry->prev_cookie, fileid, d_type);
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file->f_pos, fileid, d_type);
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if (res < 0)
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if (res < 0)
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break;
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break;
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file->f_pos = desc->target = entry->cookie;
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file->f_pos++;
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desc->target_cookie = entry->cookie;
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if (dir_decode(desc) != 0) {
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if (dir_decode(desc) != 0) {
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desc->page_index ++;
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desc->page_index ++;
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break;
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break;
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@ -369,10 +425,12 @@ int nfs_do_filldir(nfs_readdir_descriptor_t *desc, void *dirent,
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schedule();
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schedule();
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}
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}
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}
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}
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ctx->dir_pos = file->f_pos;
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ctx->dir_cookie = desc->target_cookie;
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dir_page_release(desc);
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dir_page_release(desc);
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if (dentry != NULL)
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if (dentry != NULL)
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dput(dentry);
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dput(dentry);
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dfprintk(VFS, "NFS: nfs_do_filldir() filling ended @ cookie %Lu; returning = %d\n", (long long)desc->target, res);
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dfprintk(VFS, "NFS: nfs_do_filldir() filling ended @ cookie %Lu; returning = %d\n", (long long)desc->target_cookie, res);
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return res;
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return res;
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}
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}
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@ -398,14 +456,14 @@ int uncached_readdir(nfs_readdir_descriptor_t *desc, void *dirent,
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struct page *page = NULL;
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struct page *page = NULL;
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int status;
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int status;
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dfprintk(VFS, "NFS: uncached_readdir() searching for cookie %Lu\n", (long long)desc->target);
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dfprintk(VFS, "NFS: uncached_readdir() searching for cookie %Lu\n", (long long)desc->target_cookie);
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page = alloc_page(GFP_HIGHUSER);
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page = alloc_page(GFP_HIGHUSER);
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if (!page) {
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if (!page) {
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status = -ENOMEM;
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status = -ENOMEM;
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goto out;
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goto out;
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}
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}
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desc->error = NFS_PROTO(inode)->readdir(file->f_dentry, cred, desc->target,
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desc->error = NFS_PROTO(inode)->readdir(file->f_dentry, cred, desc->target_cookie,
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page,
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page,
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NFS_SERVER(inode)->dtsize,
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NFS_SERVER(inode)->dtsize,
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desc->plus);
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desc->plus);
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@ -414,7 +472,7 @@ int uncached_readdir(nfs_readdir_descriptor_t *desc, void *dirent,
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desc->ptr = kmap(page); /* matching kunmap in nfs_do_filldir */
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desc->ptr = kmap(page); /* matching kunmap in nfs_do_filldir */
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if (desc->error >= 0) {
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if (desc->error >= 0) {
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if ((status = dir_decode(desc)) == 0)
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if ((status = dir_decode(desc)) == 0)
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desc->entry->prev_cookie = desc->target;
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desc->entry->prev_cookie = desc->target_cookie;
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} else
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} else
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status = -EIO;
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status = -EIO;
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if (status < 0)
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if (status < 0)
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@ -435,13 +493,15 @@ int uncached_readdir(nfs_readdir_descriptor_t *desc, void *dirent,
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goto out;
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goto out;
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}
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}
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/* The file offset position is now represented as a true offset into the
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/* The file offset position represents the dirent entry number. A
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* page cache as is the case in most of the other filesystems.
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last cookie cache takes care of the common case of reading the
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whole directory.
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*/
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*/
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static int nfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
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static int nfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
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{
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{
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struct dentry *dentry = filp->f_dentry;
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struct dentry *dentry = filp->f_dentry;
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struct inode *inode = dentry->d_inode;
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struct inode *inode = dentry->d_inode;
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struct nfs_open_context *ctx = filp->private_data;
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nfs_readdir_descriptor_t my_desc,
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nfs_readdir_descriptor_t my_desc,
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*desc = &my_desc;
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*desc = &my_desc;
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struct nfs_entry my_entry;
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struct nfs_entry my_entry;
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@ -458,17 +518,22 @@ static int nfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
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}
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}
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/*
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/*
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* filp->f_pos points to the file offset in the page cache.
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* filp->f_pos points to the dirent entry number.
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* but if the cache has meanwhile been zapped, we need to
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* ctx->dir_pos has the number of the cached cookie. We have
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* read from the last dirent to revalidate f_pos
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* to either find the entry with the appropriate number or
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* itself.
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* revalidate the cookie.
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*/
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*/
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memset(desc, 0, sizeof(*desc));
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memset(desc, 0, sizeof(*desc));
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desc->file = filp;
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desc->file = filp;
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desc->target = filp->f_pos;
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desc->decode = NFS_PROTO(inode)->decode_dirent;
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desc->decode = NFS_PROTO(inode)->decode_dirent;
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desc->plus = NFS_USE_READDIRPLUS(inode);
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desc->plus = NFS_USE_READDIRPLUS(inode);
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desc->target_index = filp->f_pos;
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if (filp->f_pos == ctx->dir_pos)
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desc->target_cookie = ctx->dir_cookie;
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else
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desc->target_cookie = 0;
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my_entry.cookie = my_entry.prev_cookie = 0;
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my_entry.cookie = my_entry.prev_cookie = 0;
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my_entry.eof = 0;
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my_entry.eof = 0;
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@ -478,9 +543,10 @@ static int nfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
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while(!desc->entry->eof) {
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while(!desc->entry->eof) {
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res = readdir_search_pagecache(desc);
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res = readdir_search_pagecache(desc);
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if (res == -EBADCOOKIE) {
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if (res == -EBADCOOKIE) {
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/* This means either end of directory */
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/* This means either end of directory */
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if (desc->entry->cookie != desc->target) {
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if (desc->target_cookie && desc->entry->cookie != desc->target_cookie) {
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/* Or that the server has 'lost' a cookie */
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/* Or that the server has 'lost' a cookie */
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res = uncached_readdir(desc, dirent, filldir);
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res = uncached_readdir(desc, dirent, filldir);
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if (res >= 0)
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if (res >= 0)
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@ -891,6 +891,8 @@ struct nfs_open_context *alloc_nfs_open_context(struct dentry *dentry, struct rp
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ctx->state = NULL;
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ctx->state = NULL;
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ctx->lockowner = current->files;
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ctx->lockowner = current->files;
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ctx->error = 0;
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ctx->error = 0;
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ctx->dir_pos = 0;
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ctx->dir_cookie = 0;
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}
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}
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return ctx;
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return ctx;
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}
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}
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@ -84,6 +84,9 @@ struct nfs_open_context {
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int error;
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int error;
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struct list_head list;
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struct list_head list;
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int dir_pos; /* Directory cookie cache */
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__u64 dir_cookie;
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};
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};
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/*
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/*
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