On 4/16/25 11:07, Miklos Szeredi wrote:
> When getting the directory contents, the entries are fist fetched to a
> kernel buffer, then they are copied to userspace with dir_emit(). This
> second phase is non-blocking as long as the userspace buffer is not paged
> out, making it interruptible makes zero sense.
>
> Overload d_type as flags, since it only uses 4 bits from 32.
>
> Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxxxxx>
> ---
> fs/fuse/readdir.c | 4 ++--
> fs/readdir.c | 15 ++++++++++++---
> include/linux/fs.h | 3 +++
> 3 files changed, 17 insertions(+), 5 deletions(-)
>
> diff --git a/fs/fuse/readdir.c b/fs/fuse/readdir.c
> index 17ce9636a2b1..edcd6f18a8a8 100644
> --- a/fs/fuse/readdir.c
> +++ b/fs/fuse/readdir.c
> @@ -120,7 +120,7 @@ static bool fuse_emit(struct file *file, struct dir_context *ctx,
> fuse_add_dirent_to_cache(file, dirent, ctx->pos);
>
> return dir_emit(ctx, dirent->name, dirent->namelen, dirent->ino,
> - dirent->type);
> + dirent->type | FILLDIR_FLAG_NOINTR);
> }
>
> static int parse_dirfile(char *buf, size_t nbytes, struct file *file,
> @@ -419,7 +419,7 @@ static enum fuse_parse_result fuse_parse_cache(struct fuse_file *ff,
> if (ff->readdir.pos == ctx->pos) {
> res = FOUND_SOME;
> if (!dir_emit(ctx, dirent->name, dirent->namelen,
> - dirent->ino, dirent->type))
> + dirent->ino, dirent->type | FILLDIR_FLAG_NOINTR))
> return FOUND_ALL;
> ctx->pos = dirent->off;
> }
> diff --git a/fs/readdir.c b/fs/readdir.c
> index 0038efda417b..00ceae3fc2e3 100644
> --- a/fs/readdir.c
> +++ b/fs/readdir.c
> @@ -266,6 +266,9 @@ static bool filldir(struct dir_context *ctx, const char *name, int namlen,
> int reclen = ALIGN(offsetof(struct linux_dirent, d_name) + namlen + 2,
> sizeof(long));
> int prev_reclen;
> + unsigned int flags = d_type;
> +
> + d_type &= S_DT_MASK;
>
> buf->error = verify_dirent_name(name, namlen);
> if (unlikely(buf->error))
> @@ -279,7 +282,7 @@ static bool filldir(struct dir_context *ctx, const char *name, int namlen,
> return false;
> }
> prev_reclen = buf->prev_reclen;
> - if (prev_reclen && signal_pending(current))
> + if (!(flags & FILLDIR_FLAG_NOINTR) && prev_reclen && signal_pending(current))
> return false;
> dirent = buf->current_dir;
> prev = (void __user *) dirent - prev_reclen;
> @@ -351,6 +354,9 @@ static bool filldir64(struct dir_context *ctx, const char *name, int namlen,
> int reclen = ALIGN(offsetof(struct linux_dirent64, d_name) + namlen + 1,
> sizeof(u64));
> int prev_reclen;
> + unsigned int flags = d_type;
> +
> + d_type &= S_DT_MASK;
>
> buf->error = verify_dirent_name(name, namlen);
> if (unlikely(buf->error))
> @@ -359,7 +365,7 @@ static bool filldir64(struct dir_context *ctx, const char *name, int namlen,
> if (reclen > buf->count)
> return false;
> prev_reclen = buf->prev_reclen;
> - if (prev_reclen && signal_pending(current))
> + if (!(flags & FILLDIR_FLAG_NOINTR) && prev_reclen && signal_pending(current))
> return false;
> dirent = buf->current_dir;
> prev = (void __user *)dirent - prev_reclen;
> @@ -513,6 +519,9 @@ static bool compat_filldir(struct dir_context *ctx, const char *name, int namlen
> int reclen = ALIGN(offsetof(struct compat_linux_dirent, d_name) +
> namlen + 2, sizeof(compat_long_t));
> int prev_reclen;
> + unsigned int flags = d_type;
> +
> + d_type &= S_DT_MASK;
>
> buf->error = verify_dirent_name(name, namlen);
> if (unlikely(buf->error))
> @@ -526,7 +535,7 @@ static bool compat_filldir(struct dir_context *ctx, const char *name, int namlen
> return false;
> }
> prev_reclen = buf->prev_reclen;
> - if (prev_reclen && signal_pending(current))
> + if (!(flags & FILLDIR_FLAG_NOINTR) && prev_reclen && signal_pending(current))
> return false;
> dirent = buf->current_dir;
> prev = (void __user *) dirent - prev_reclen;
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 016b0fe1536e..0f2a1a572e3a 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -2073,6 +2073,9 @@ struct dir_context {
> loff_t pos;
> };
>
> +/* If OR-ed with d_type, pending signals are not checked */
> +#define FILLDIR_FLAG_NOINTR 0x1000
This is the part that might be confusing - it is in another
file than DT_MAX / S_DT_MASK - it might be hard to know about
FILLDIR_FLAG_NOINTR and possible other future flags?
But then it is certainly not a file type, having it in fs.h
makes sense from that point of view.
Reviewed-by: Bernd Schubert <bschubert@xxxxxxx>
