From 00a926422765064cb28e218d4837411c88bf6a3e Mon Sep 17 00:00:00 2001 From: Olivier Galibert Date: Wed, 22 Jun 2005 17:16:29 +0000 Subject: [PATCH] [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 Signed-off-by: Trond Myklebust --- fs/nfs/dir.c | 114 ++++++++++++++++++++++++++++++++--------- fs/nfs/inode.c | 2 + include/linux/nfs_fs.h | 3 ++ 3 files changed, 95 insertions(+), 24 deletions(-) diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c index 2c6a95945684..fceef29c65a3 100644 --- a/fs/nfs/dir.c +++ b/fs/nfs/dir.c @@ -141,7 +141,9 @@ typedef struct { struct page *page; unsigned long page_index; u32 *ptr; - u64 target; + u64 target_cookie; + int target_index; + int current_index; struct nfs_entry *entry; decode_dirent_t decode; int plus; @@ -225,14 +227,14 @@ void dir_page_release(nfs_readdir_descriptor_t *desc) /* * Given a pointer to a buffer that has already been filled by a call - * to readdir, find the next entry. + * to readdir, find the next entry with cookie 'desc->target_cookie'. * * If the end of the buffer has been reached, return -EAGAIN, if not, * return the offset within the buffer of the next entry to be * read. */ static inline -int find_dirent(nfs_readdir_descriptor_t *desc, struct page *page) +int find_dirent(nfs_readdir_descriptor_t *desc) { struct nfs_entry *entry = desc->entry; int loop_count = 0, @@ -240,7 +242,7 @@ int find_dirent(nfs_readdir_descriptor_t *desc, struct page *page) while((status = dir_decode(desc)) == 0) { dfprintk(VFS, "NFS: found cookie %Lu\n", (long long)entry->cookie); - if (entry->prev_cookie == desc->target) + if (entry->prev_cookie == desc->target_cookie) break; if (loop_count++ > 200) { loop_count = 0; @@ -252,8 +254,44 @@ int find_dirent(nfs_readdir_descriptor_t *desc, struct page *page) } /* - * Find the given page, and call find_dirent() in order to try to - * return the next entry. + * Given a pointer to a buffer that has already been filled by a call + * to readdir, find the entry at offset 'desc->target_index'. + * + * If the end of the buffer has been reached, return -EAGAIN, if not, + * return the offset within the buffer of the next entry to be + * read. + */ +static inline +int find_dirent_index(nfs_readdir_descriptor_t *desc) +{ + struct nfs_entry *entry = desc->entry; + int loop_count = 0, + status; + + for(;;) { + status = dir_decode(desc); + if (status) + break; + + dfprintk(VFS, "NFS: found cookie %Lu at index %d\n", (long long)entry->cookie, desc->current_index); + + if (desc->target_index == desc->current_index) { + desc->target_cookie = entry->cookie; + break; + } + desc->current_index++; + if (loop_count++ > 200) { + loop_count = 0; + schedule(); + } + } + dfprintk(VFS, "NFS: find_dirent_index() returns %d\n", status); + return status; +} + +/* + * Find the given page, and call find_dirent() or find_dirent_index in + * order to try to return the next entry. */ static inline int find_dirent_page(nfs_readdir_descriptor_t *desc) @@ -276,7 +314,10 @@ int find_dirent_page(nfs_readdir_descriptor_t *desc) /* NOTE: Someone else may have changed the READDIRPLUS flag */ desc->page = page; desc->ptr = kmap(page); /* matching kunmap in nfs_do_filldir */ - status = find_dirent(desc, page); + if (desc->target_cookie) + status = find_dirent(desc); + else + status = find_dirent_index(desc); if (status < 0) dir_page_release(desc); out: @@ -291,7 +332,8 @@ int find_dirent_page(nfs_readdir_descriptor_t *desc) * Recurse through the page cache pages, and return a * filled nfs_entry structure of the next directory entry if possible. * - * The target for the search is 'desc->target'. + * The target for the search is 'desc->target_cookie' if non-0, + * 'desc->target_index' otherwise */ static inline int readdir_search_pagecache(nfs_readdir_descriptor_t *desc) @@ -299,7 +341,19 @@ int readdir_search_pagecache(nfs_readdir_descriptor_t *desc) int loop_count = 0; int res; - dfprintk(VFS, "NFS: readdir_search_pagecache() searching for cookie %Lu\n", (long long)desc->target); + if (desc->target_cookie) + dfprintk(VFS, "NFS: readdir_search_pagecache() searching for cookie %Lu\n", (long long)desc->target_cookie); + else + dfprintk(VFS, "NFS: readdir_search_pagecache() searching for cookie number %d\n", desc->target_index); + + /* Always search-by-index from the beginning of the cache */ + if (!(desc->target_cookie)) { + desc->page_index = 0; + desc->entry->cookie = desc->entry->prev_cookie = 0; + desc->entry->eof = 0; + desc->current_index = 0; + } + for (;;) { res = find_dirent_page(desc); if (res != -EAGAIN) @@ -332,11 +386,12 @@ int nfs_do_filldir(nfs_readdir_descriptor_t *desc, void *dirent, struct file *file = desc->file; struct nfs_entry *entry = desc->entry; struct dentry *dentry = NULL; + struct nfs_open_context *ctx = file->private_data; unsigned long fileid; int loop_count = 0, res; - dfprintk(VFS, "NFS: nfs_do_filldir() filling starting @ cookie %Lu\n", (long long)desc->target); + dfprintk(VFS, "NFS: nfs_do_filldir() filling starting @ cookie %Lu\n", (long long)entry->cookie); for(;;) { unsigned d_type = DT_UNKNOWN; @@ -356,10 +411,11 @@ int nfs_do_filldir(nfs_readdir_descriptor_t *desc, void *dirent, } res = filldir(dirent, entry->name, entry->len, - entry->prev_cookie, fileid, d_type); + file->f_pos, fileid, d_type); if (res < 0) break; - file->f_pos = desc->target = entry->cookie; + file->f_pos++; + desc->target_cookie = entry->cookie; if (dir_decode(desc) != 0) { desc->page_index ++; break; @@ -369,10 +425,12 @@ int nfs_do_filldir(nfs_readdir_descriptor_t *desc, void *dirent, schedule(); } } + ctx->dir_pos = file->f_pos; + ctx->dir_cookie = desc->target_cookie; dir_page_release(desc); if (dentry != NULL) dput(dentry); - dfprintk(VFS, "NFS: nfs_do_filldir() filling ended @ cookie %Lu; returning = %d\n", (long long)desc->target, res); + dfprintk(VFS, "NFS: nfs_do_filldir() filling ended @ cookie %Lu; returning = %d\n", (long long)desc->target_cookie, res); return res; } @@ -398,14 +456,14 @@ int uncached_readdir(nfs_readdir_descriptor_t *desc, void *dirent, struct page *page = NULL; int status; - dfprintk(VFS, "NFS: uncached_readdir() searching for cookie %Lu\n", (long long)desc->target); + dfprintk(VFS, "NFS: uncached_readdir() searching for cookie %Lu\n", (long long)desc->target_cookie); page = alloc_page(GFP_HIGHUSER); if (!page) { status = -ENOMEM; goto out; } - desc->error = NFS_PROTO(inode)->readdir(file->f_dentry, cred, desc->target, + desc->error = NFS_PROTO(inode)->readdir(file->f_dentry, cred, desc->target_cookie, page, NFS_SERVER(inode)->dtsize, desc->plus); @@ -414,7 +472,7 @@ int uncached_readdir(nfs_readdir_descriptor_t *desc, void *dirent, desc->ptr = kmap(page); /* matching kunmap in nfs_do_filldir */ if (desc->error >= 0) { if ((status = dir_decode(desc)) == 0) - desc->entry->prev_cookie = desc->target; + desc->entry->prev_cookie = desc->target_cookie; } else status = -EIO; if (status < 0) @@ -435,13 +493,15 @@ int uncached_readdir(nfs_readdir_descriptor_t *desc, void *dirent, goto out; } -/* The file offset position is now represented as a true offset into the - * page cache as is the case in most of the other filesystems. +/* The file offset position represents the dirent entry number. A + last cookie cache takes care of the common case of reading the + whole directory. */ static int nfs_readdir(struct file *filp, void *dirent, filldir_t filldir) { struct dentry *dentry = filp->f_dentry; struct inode *inode = dentry->d_inode; + struct nfs_open_context *ctx = filp->private_data; nfs_readdir_descriptor_t my_desc, *desc = &my_desc; struct nfs_entry my_entry; @@ -458,17 +518,22 @@ static int nfs_readdir(struct file *filp, void *dirent, filldir_t filldir) } /* - * filp->f_pos points to the file offset in the page cache. - * but if the cache has meanwhile been zapped, we need to - * read from the last dirent to revalidate f_pos - * itself. + * filp->f_pos points to the dirent entry number. + * ctx->dir_pos has the number of the cached cookie. We have + * to either find the entry with the appropriate number or + * revalidate the cookie. */ memset(desc, 0, sizeof(*desc)); desc->file = filp; - desc->target = filp->f_pos; desc->decode = NFS_PROTO(inode)->decode_dirent; desc->plus = NFS_USE_READDIRPLUS(inode); + desc->target_index = filp->f_pos; + + if (filp->f_pos == ctx->dir_pos) + desc->target_cookie = ctx->dir_cookie; + else + desc->target_cookie = 0; my_entry.cookie = my_entry.prev_cookie = 0; my_entry.eof = 0; @@ -478,9 +543,10 @@ static int nfs_readdir(struct file *filp, void *dirent, filldir_t filldir) while(!desc->entry->eof) { res = readdir_search_pagecache(desc); + if (res == -EBADCOOKIE) { /* This means either end of directory */ - if (desc->entry->cookie != desc->target) { + if (desc->target_cookie && desc->entry->cookie != desc->target_cookie) { /* Or that the server has 'lost' a cookie */ res = uncached_readdir(desc, dirent, filldir); if (res >= 0) diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c index 8a8d57d9d660..9fa02e7984ac 100644 --- a/fs/nfs/inode.c +++ b/fs/nfs/inode.c @@ -891,6 +891,8 @@ struct nfs_open_context *alloc_nfs_open_context(struct dentry *dentry, struct rp ctx->state = NULL; ctx->lockowner = current->files; ctx->error = 0; + ctx->dir_pos = 0; + ctx->dir_cookie = 0; } return ctx; } diff --git a/include/linux/nfs_fs.h b/include/linux/nfs_fs.h index 4ceac9ddac93..f810195ef7ad 100644 --- a/include/linux/nfs_fs.h +++ b/include/linux/nfs_fs.h @@ -84,6 +84,9 @@ struct nfs_open_context { int error; struct list_head list; + + int dir_pos; /* Directory cookie cache */ + __u64 dir_cookie; }; /* -- 2.20.1