The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From ff002b30181d30cdfbca316dadd099c3ca0d739c Mon Sep 17 00:00:00 2001

From: Jens Axboe axboe@kernel.dk Date: Fri, 7 Feb 2020 16:05:21 -0700 Subject: [PATCH] io_uring: grab ->fs as part of async preparation

This passes it in to io-wq, so it assumes the right fs_struct when executing async work that may need to do lookups.

Cc: stable@vger.kernel.org # 5.3+ Signed-off-by: Jens Axboe axboe@kernel.dk

diff --git a/fs/io_uring.c b/fs/io_uring.c index 1a3ca6577a10..2a7bb178986e 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -75,6 +75,7 @@ #include <linux/fsnotify.h> #include <linux/fadvise.h> #include <linux/eventpoll.h> +#include <linux/fs_struct.h>

#define CREATE_TRACE_POINTS #include <trace/events/io_uring.h> @@ -611,6 +612,8 @@ struct io_op_def { unsigned not_supported : 1; /* needs file table */ unsigned file_table : 1; + /* needs ->fs */ + unsigned needs_fs : 1; };

static const struct io_op_def io_op_defs[] = { @@ -653,12 +656,14 @@ static const struct io_op_def io_op_defs[] = { .needs_mm = 1, .needs_file = 1, .unbound_nonreg_file = 1, + .needs_fs = 1, }, [IORING_OP_RECVMSG] = { .async_ctx = 1, .needs_mm = 1, .needs_file = 1, .unbound_nonreg_file = 1, + .needs_fs = 1, }, [IORING_OP_TIMEOUT] = { .async_ctx = 1, @@ -689,6 +694,7 @@ static const struct io_op_def io_op_defs[] = { .needs_file = 1, .fd_non_neg = 1, .file_table = 1, + .needs_fs = 1, }, [IORING_OP_CLOSE] = { .needs_file = 1, @@ -702,6 +708,7 @@ static const struct io_op_def io_op_defs[] = { .needs_mm = 1, .needs_file = 1, .fd_non_neg = 1, + .needs_fs = 1, }, [IORING_OP_READ] = { .needs_mm = 1, @@ -733,6 +740,7 @@ static const struct io_op_def io_op_defs[] = { .needs_file = 1, .fd_non_neg = 1, .file_table = 1, + .needs_fs = 1, }, [IORING_OP_EPOLL_CTL] = { .unbound_nonreg_file = 1, @@ -907,6 +915,16 @@ static inline void io_req_work_grab_env(struct io_kiocb *req, } if (!req->work.creds) req->work.creds = get_current_cred(); + if (!req->work.fs && def->needs_fs) { + spin_lock(&current->fs->lock); + if (!current->fs->in_exec) { + req->work.fs = current->fs; + req->work.fs->users++; + } else { + req->work.flags |= IO_WQ_WORK_CANCEL; + } + spin_unlock(&current->fs->lock); + } }

static inline void io_req_work_drop_env(struct io_kiocb *req) @@ -919,6 +937,16 @@ static inline void io_req_work_drop_env(struct io_kiocb *req) put_cred(req->work.creds); req->work.creds = NULL; } + if (req->work.fs) { + struct fs_struct *fs = req->work.fs; + + spin_lock(&req->work.fs->lock); + if (--fs->users) + fs = NULL; + spin_unlock(&req->work.fs->lock); + if (fs) + free_fs_struct(fs); + } }

static inline bool io_prep_async_work(struct io_kiocb *req,