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[91.82.182.24]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-acb3cd61a92sm87056166b.5.2025.04.16.02.07.29 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 16 Apr 2025 02:07:29 -0700 (PDT) From: Miklos Szeredi To: linux-fsdevel@vger.kernel.org Subject: [RFC PATCH] fuse: don't allow signals to interrupt getdents copying Date: Wed, 16 Apr 2025 11:07:27 +0200 Message-ID: <20250416090728.923460-1-mszeredi@redhat.com> X-Mailer: git-send-email 2.49.0 Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 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 Reviewed-by: Bernd Schubert --- 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 + /* * These flags let !MMU mmap() govern direct device mapping vs immediate * copying more easily for MAP_PRIVATE, especially for ROM filesystems.