Messages in this thread Patch in this message | | | From | Kent Overstreet <> | Subject | [PATCH] aio: Fix return code of io_submit() (RFC) | Date | Fri, 3 Oct 2014 11:08:13 -0700 |
| |
io_submit() could return -EAGAIN on memory allocation failure when it should really have been returning -ENOMEM. This could confuse applications (i.e. fio) since -EAGAIN means "too many requests outstanding, wait until completions have been reaped" and if the application actually was tracking outstanding completions this wouldn't make a lot of sense.
NOTE:
the man page seems to imply that the current behaviour (-EAGAIN on allocation failure) has always been the case. I don't think it makes a lot of sense, but this should probably be discussed more widely in case applications have somehow come to rely on the current behaviour...
Signed-off-by: Kent Overstreet <kmo@daterainc.com> Cc: Benjamin LaHaise <bcrl@kvack.org> Cc: Zach Brown <zab@zabbo.net> Cc: Jeff Moyer <jmoyer@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Slava Pestov <sp@daterainc.com> --- fs/aio.c | 26 +++++++++++++------------- 1 file changed, 13 insertions(+), 13 deletions(-)
diff --git a/fs/aio.c b/fs/aio.c index 733750096b..556547044b 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -933,23 +933,14 @@ static inline struct kiocb *aio_get_req(struct kioctx *ctx) { struct kiocb *req; - if (!get_reqs_available(ctx)) { - user_refill_reqs_available(ctx); - if (!get_reqs_available(ctx)) - return NULL; - } - req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL|__GFP_ZERO); if (unlikely(!req)) - goto out_put; + return NULL; percpu_ref_get(&ctx->reqs); req->ki_ctx = ctx; return req; -out_put: - put_reqs_available(ctx, 1); - return NULL; } static void kiocb_free(struct kiocb *req) @@ -1489,9 +1480,17 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb, return -EINVAL; } + if (!get_reqs_available(ctx)) { + user_refill_reqs_available(ctx); + if (!get_reqs_available(ctx)) + return -EAGAIN; + } + req = aio_get_req(ctx); - if (unlikely(!req)) - return -EAGAIN; + if (unlikely(!req)) { + ret = -ENOMEM; + goto out_put; + } req->ki_filp = fget(iocb->aio_fildes); if (unlikely(!req->ki_filp)) { @@ -1533,9 +1532,10 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb, return 0; out_put_req: - put_reqs_available(ctx, 1); percpu_ref_put(&ctx->reqs); kiocb_free(req); +out_put: + put_reqs_available(ctx, 1); return ret; } -- 2.1.1
| |