From: Chuck Lever <chuck.lever@xxxxxxxxxx> The new directory offset helpers don't conform with the convention of getdents() returning no more entries once a directory file descriptor has reached the current end-of-directory. To address this, copy the logic from dcache_readdir() to mark the open directory file descriptor once EOD has been reached. Seeking resets the mark. Reported-by: Tavian Barnes <tavianator@xxxxxxxxxxxxxx> Closes: https://lore.kernel.org/linux-fsdevel/20231113180616.2831430-1-tavianator@xxxxxxxxxxxxxx/ Fixes: 6faddda69f62 ("libfs: Add directory operations for stable offsets") Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx> --- fs/libfs.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) v4 of this patch passes Tavian's reproducer and fstests over NFS and directly on a tmpfs mount. Changes since v3: - Ensure that llseek() resets the EOD mark too Changes since v2: - Go back to marking EOD in the file->private_data field Changes since RFC: - Keep file->private_data stable while directory descriptor remains open diff --git a/fs/libfs.c b/fs/libfs.c index e9440d55073c..c2aa6fd4795c 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -399,6 +399,8 @@ static loff_t offset_dir_llseek(struct file *file, loff_t offset, int whence) return -EINVAL; } + /* In this case, ->private_data is protected by f_pos_lock */ + file->private_data = NULL; return vfs_setpos(file, offset, U32_MAX); } @@ -428,7 +430,7 @@ static bool offset_dir_emit(struct dir_context *ctx, struct dentry *dentry) inode->i_ino, fs_umode_to_dtype(inode->i_mode)); } -static void offset_iterate_dir(struct inode *inode, struct dir_context *ctx) +static void *offset_iterate_dir(struct inode *inode, struct dir_context *ctx) { struct offset_ctx *so_ctx = inode->i_op->get_offset_ctx(inode); XA_STATE(xas, &so_ctx->xa, ctx->pos); @@ -437,7 +439,7 @@ static void offset_iterate_dir(struct inode *inode, struct dir_context *ctx) while (true) { dentry = offset_find_next(&xas); if (!dentry) - break; + return ERR_PTR(-ENOENT); if (!offset_dir_emit(ctx, dentry)) { dput(dentry); @@ -447,6 +449,7 @@ static void offset_iterate_dir(struct inode *inode, struct dir_context *ctx) dput(dentry); ctx->pos = xas.xa_index + 1; } + return NULL; } /** @@ -479,7 +482,12 @@ static int offset_readdir(struct file *file, struct dir_context *ctx) if (!dir_emit_dots(file, ctx)) return 0; - offset_iterate_dir(d_inode(dir), ctx); + /* In this case, ->private_data is protected by f_pos_lock */ + if (ctx->pos == 2) + file->private_data = NULL; + else if (file->private_data == ERR_PTR(-ENOENT)) + return 0; + file->private_data = offset_iterate_dir(d_inode(dir), ctx); return 0; }
