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Clarify zpool_events_next() comment

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Due to the very poorly chosen argument name 'cleanup_fd' it was
completely unclear that this file descriptor is used to track the
current cursor location.  When the file descriptor is created by
opening ZFS_DEV a private cursor is created in the kernel for the
returned file descriptor.  Subsequent calls to zpool_events_next()
and zpool_events_seek() then require the file descriptor as an
argument to reposition the cursor.  When the file descriptor is
closed the kernel state tracking the cursor is destroyed.

This patch contains no functional change, it just changes a
few variable names and clarifies the documentation.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Chris Dunlap <cdunlap@llnl.gov>
Issue #2
This commit is contained in:
Brian Behlendorf 2013-11-22 16:00:39 -08:00
parent 75e3ff58fe
commit 9b101a7320
3 changed files with 16 additions and 16 deletions
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10
cmd/zpool/zpool_main.c
View File

@ -5455,17 +5455,17 @@ static int
zpool_do_events_next(ev_opts_t *opts)
{
nvlist_t *nvl;
int cleanup_fd, ret, dropped;
int zevent_fd, ret, dropped;
cleanup_fd = open(ZFS_DEV, O_RDWR);
VERIFY(cleanup_fd >= 0);
zevent_fd = open(ZFS_DEV, O_RDWR);
VERIFY(zevent_fd >= 0);
if (!opts->scripted)
(void) printf(gettext("%-30s %s\n"), "TIME", "CLASS");
while (1) {
ret = zpool_events_next(g_zfs, &nvl, &dropped,
!!opts->follow, cleanup_fd);
!!opts->follow, zevent_fd);
if (ret || nvl == NULL)
break;
@ -5483,7 +5483,7 @@ zpool_do_events_next(ev_opts_t *opts)
nvlist_free(nvl);
}
VERIFY(0 == close(cleanup_fd));
VERIFY(0 == close(zevent_fd));
return (ret);
}

20
lib/libzfs/libzfs_pool.c
View File

@ -3783,25 +3783,25 @@ zpool_get_history(zpool_handle_t *zhp, nvlist_t **nvhisp)
}
/*
* Retrieve the next event. If there is a new event available 'nvp' will
* contain a newly allocated nvlist and 'dropped' will be set to the number
* of missed events since the last call to this function. When 'nvp' is
* set to NULL it indicates no new events are available. In either case
* the function returns 0 and it is up to the caller to free 'nvp'. In
* the case of a fatal error the function will return a non-zero value.
* When the function is called in blocking mode it will not return until
* a new event is available.
* Retrieve the next event given the passed 'zevent_fd' file descriptor.
* If there is a new event available 'nvp' will contain a newly allocated
* nvlist and 'dropped' will be set to the number of missed events since
* the last call to this function. When 'nvp' is set to NULL it indicates
* no new events are available. In either case the function returns 0 and
* it is up to the caller to free 'nvp'. In the case of a fatal error the
* function will return a non-zero value. When the function is called in
* blocking mode it will not return until a new event is available.
*/
int
zpool_events_next(libzfs_handle_t *hdl, nvlist_t **nvp,
int *dropped, int block, int cleanup_fd)
int *dropped, int block, int zevent_fd)
{
zfs_cmd_t zc = {"\0"};
int error = 0;
*nvp = NULL;
*dropped = 0;
zc.zc_cleanup_fd = cleanup_fd;
zc.zc_cleanup_fd = zevent_fd;
if (!block)
zc.zc_guid = ZEVENT_NONBLOCK;

2
module/zfs/zfs_ioctl.c
View File

@ -4860,11 +4860,11 @@ zfs_ioc_release(const char *pool, nvlist_t *holds, nvlist_t *errlist)
/*
* inputs:
* zc_guid flags (ZEVENT_NONBLOCK)
* zc_cleanup_fd zevent file descriptor
*
* outputs:
* zc_nvlist_dst next nvlist event
* zc_cookie dropped events since last get
* zc_cleanup_fd cleanup-on-exit file descriptor
*/
static int
zfs_ioc_events_next(zfs_cmd_t *zc)