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lio_listio: return EAGAIN instead of EIO when out of resources

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This behavior is already documented by the man page, and suggested by POSIX.

Reviewed by:	jhb
MFC after:	3 weeks
Differential Revision:	https://reviews.freebsd.org/D15099
This commit is contained in:
Alan Somers 2018-04-16 18:12:15 +00:00
parent eec02418d8
commit 52c0983128
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=332631
3 changed files with 82 additions and 3 deletions
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12
sys/kern/vfs_aio.c
View File

@ -2131,7 +2131,7 @@ kern_lio_listio(struct thread *td, int mode, struct aiocb * const *uacb_list,
struct aioliojob *lj;
struct kevent kev;
int error;
int nerror;
int nagain, nerror;
int i;
if ((mode != LIO_NOWAIT) && (mode != LIO_WAIT))
@ -2200,12 +2200,15 @@ kern_lio_listio(struct thread *td, int mode, struct aiocb * const *uacb_list,
/*
* Get pointers to the list of I/O requests.
*/
nagain = 0;
nerror = 0;
for (i = 0; i < nent; i++) {
job = acb_list[i];
if (job != NULL) {
error = aio_aqueue(td, job, lj, LIO_NOP, ops);
if (error != 0)
if (error == EAGAIN)
nagain++;
else if (error != 0)
nerror++;
}
}
@ -2252,7 +2255,10 @@ kern_lio_listio(struct thread *td, int mode, struct aiocb * const *uacb_list,
if (nerror)
return (EIO);
return (error);
else if (nagain)
return (EAGAIN);
else
return (error);
}
/* syscall - list directed I/O (REALTIME) */

2
tests/sys/aio/Makefile
View File

@ -6,6 +6,8 @@ ATF_TESTS_C+= aio_test
ATF_TESTS_C+= lio_test
TEST_METADATA.aio_test+= timeout="30"
TEST_METADATA.lio_test+= timeout="10"
# Some lio_test testcases involve system resource limitations, so cannot run concurrently
TEST_METADATA.lio_test+= is_exclusive=true
PLAIN_TESTS_C+= aio_kqueue_test
PLAIN_TESTS_C+= lio_kqueue_test

71
tests/sys/aio/lio_test.c
View File

@ -30,10 +30,13 @@
#include <sys/event.h>
#include <aio.h>
#include <fcntl.h>
#include <semaphore.h>
#include <stdlib.h>
#include <atf-c.h>
#include "local.h"
#include "freebsd_test_suite/macros.h"
static sem_t completions;
@ -51,6 +54,73 @@ thr_handler(union sigval sv __unused)
ATF_REQUIRE_EQ(0, sem_post(&completions));
}
/*
* If lio_listio is unable to enqueue any requests at all, it should return
* EAGAIN.
*/
ATF_TC_WITHOUT_HEAD(lio_listio_eagain_kevent);
ATF_TC_BODY(lio_listio_eagain_kevent, tc)
{
int fd, i, j, kq, max_queue_per_proc, ios_per_call;
size_t max_queue_per_proc_size;
struct aiocb *aiocbs[2];
struct aiocb **list[2];
struct sigevent sev[2];
char *buffer;
const char *path="tempfile";
void *udata[2];
ATF_REQUIRE_KERNEL_MODULE("aio");
ATF_REQUIRE_UNSAFE_AIO();
max_queue_per_proc_size = sizeof(max_queue_per_proc);
ATF_REQUIRE_EQ(sysctlbyname("vfs.aio.max_aio_queue_per_proc",
&max_queue_per_proc, &max_queue_per_proc_size, NULL, 0), 0);
ios_per_call = max_queue_per_proc;
fd = open(path, O_RDWR|O_CREAT, 0666);
ATF_REQUIRE(fd >= 0);
kq = kqueue();
ATF_REQUIRE(kq > 0);
buffer = calloc(1, 4096);
ATF_REQUIRE(buffer != NULL);
/*
* Call lio_listio twice, each with the maximum number of operations.
* The first call should succeed and the second should fail.
*/
for (i = 0; i < 2; i++) {
aiocbs[i] = calloc(ios_per_call, sizeof(struct aiocb));
ATF_REQUIRE(aiocbs[i] != NULL);
list[i] = calloc(ios_per_call, sizeof(struct aiocb*));
ATF_REQUIRE(list[i] != NULL);
udata[i] = (void*)((caddr_t)0xdead0000 + i);
sev[i].sigev_notify = SIGEV_KEVENT;
sev[i].sigev_notify_kqueue = kq;
sev[i].sigev_value.sival_ptr = udata[i];
for (j = 0; j < ios_per_call; j++) {
aiocbs[i][j].aio_fildes = fd;
aiocbs[i][j].aio_offset = (i * ios_per_call + j) * 4096;
aiocbs[i][j].aio_buf = buffer;
aiocbs[i][j].aio_nbytes = 4096;
aiocbs[i][j].aio_lio_opcode = LIO_WRITE;
list[i][j] = &aiocbs[i][j];
}
}
ATF_REQUIRE_EQ(0, lio_listio(LIO_NOWAIT, list[0], ios_per_call, &sev[0]));
ATF_REQUIRE_EQ(-1, lio_listio(LIO_NOWAIT, list[1], ios_per_call, &sev[1]));
/*
* The second lio_listio call should fail with EAGAIN. Bad timing may
* mean that some requests did get enqueued, but the result should
* still be EAGAIN.
*/
ATF_REQUIRE_EQ(errno, EAGAIN);
}
/* With LIO_WAIT, an empty lio_listio should return immediately */
ATF_TC_WITHOUT_HEAD(lio_listio_empty_wait);
ATF_TC_BODY(lio_listio_empty_wait, tc)
@ -136,6 +206,7 @@ ATF_TC_BODY(lio_listio_empty_nowait_thread, tc)
ATF_TP_ADD_TCS(tp)
{
ATF_TP_ADD_TC(tp, lio_listio_eagain_kevent);
ATF_TP_ADD_TC(tp, lio_listio_empty_nowait_kevent);
ATF_TP_ADD_TC(tp, lio_listio_empty_nowait_signal);
ATF_TP_ADD_TC(tp, lio_listio_empty_nowait_thread);