On Sat, Nov 18, 2023 at 02:33:19PM -0500, Chuck Lever wrote: > 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. Rewinding > 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 | 12 +++++++++--- > 1 file changed, 9 insertions(+), 3 deletions(-) > > This patch passes Tavian's reproducer. fstests over NFS shows no > regression. However, generic/676 fails when running directly against > a tmpfs mount: > > QA output created by 676 > -All tests passed > +Unexpected EOF while reading dir. > > I will look into that. offset_dir_llseek() has to reset the file descriptor's EOD marker, just like dcache_dir_lseek() does (effectively it resets cursor->d_child). We don't hold f_pos_lock in offset_dir_llseek(), though. > Changes since v2: > - Go back to marking EOD in file->private_data (with a comment) > > 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..851e29fdd7e7 100644 > --- a/fs/libfs.c > +++ b/fs/libfs.c > @@ -428,7 +428,7 @@ 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 +437,7 @@ 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 +447,7 @@ static void offset_iterate_dir(struct inode *inode, struct dir_context *ctx) > dput(dentry); > ctx->pos = xas.xa_index + 1; > } > + return NULL; > } > > /** > @@ -479,7 +480,12 @@ 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; > } > > > -- Chuck Lever
