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| author | Karel Zak <kzak@redhat.com> | 2024-01-22 13:04:44 +0100 |
|---|---|---|
| committer | Karel Zak <kzak@redhat.com> | 2024-01-22 13:04:44 +0100 |
| commit | a2b5a4e0adf9543843bb0aef94d21e7105cf8159 (patch) | |
| tree | fa94846d66d81b97422c188d55e0896b55eead92 | |
| parent | 9218c9678a6aa9b163705364246ed128e94fabb7 (diff) | |
| download | util-linux-a2b5a4e0adf9543843bb0aef94d21e7105cf8159.tar.gz | |
libmount: ignore unwanted kernel events in monitor
If the mount operation requires multiple steps, it's optimal for the
libmount monitor to ignore the steps until we get a complete mount
(reported by the utab.event file).
This commit adds a new API function, mnt_monitor_veil_kernel(), to
ignore unwanted kernel mount events.
Note that this only makes sense when the application monitors kernel
and userspace events simultaneously.
Signed-off-by: Karel Zak <kzak@redhat.com>
| -rw-r--r-- | libmount/docs/libmount-sections.txt | 1 | ||||
| -rw-r--r-- | libmount/src/libmount.h.in | 2 | ||||
| -rw-r--r-- | libmount/src/libmount.sym | 1 | ||||
| -rw-r--r-- | libmount/src/monitor.c | 55 |
4 files changed, 54 insertions, 5 deletions
diff --git a/libmount/docs/libmount-sections.txt b/libmount/docs/libmount-sections.txt index 58e1b99f5d..0b4adb5950 100644 --- a/libmount/docs/libmount-sections.txt +++ b/libmount/docs/libmount-sections.txt @@ -456,5 +456,6 @@ mnt_monitor_get_fd mnt_monitor_close_fd mnt_monitor_next_change mnt_monitor_event_cleanup +mnt_monitor_veil_kernel mnt_monitor_wait </SECTION> diff --git a/libmount/src/libmount.h.in b/libmount/src/libmount.h.in index 97d151a693..d893c26493 100644 --- a/libmount/src/libmount.h.in +++ b/libmount/src/libmount.h.in @@ -699,6 +699,8 @@ extern int mnt_monitor_enable_kernel(struct libmnt_monitor *mn, int enable); extern int mnt_monitor_enable_userspace(struct libmnt_monitor *mn, int enable, const char *filename); +extern int mnt_monitor_veil_kernel(struct libmnt_monitor *mn, int enable); + extern int mnt_monitor_get_fd(struct libmnt_monitor *mn); extern int mnt_monitor_close_fd(struct libmnt_monitor *mn); extern int mnt_monitor_wait(struct libmnt_monitor *mn, int timeout); diff --git a/libmount/src/libmount.sym b/libmount/src/libmount.sym index 3df497bd99..0b43160f3a 100644 --- a/libmount/src/libmount.sym +++ b/libmount/src/libmount.sym @@ -379,4 +379,5 @@ MOUNT_2_39 { MOUNT_2_40 { mnt_ref_lock; mnt_unref_lock; + mnt_monitor_veil_kernel; } MOUNT_2_39; diff --git a/libmount/src/monitor.c b/libmount/src/monitor.c index ef53b6d69d..941f5d5b8e 100644 --- a/libmount/src/monitor.c +++ b/libmount/src/monitor.c @@ -64,6 +64,8 @@ struct libmnt_monitor { int fd; /* public monitor file descriptor */ struct list_head ents; + + unsigned int kernel_veiled: 1; }; struct monitor_opers { @@ -471,12 +473,28 @@ err: return rc; } +static int kernel_event_verify(struct libmnt_monitor *mn, + struct monitor_entry *me) +{ + int status = 1; + + if (!mn || !me || me->fd < 0) + return 0; + + if (mn->kernel_veiled && access(MNT_PATH_UTAB ".act", F_OK) == 0) { + status = 0; + DBG(MONITOR, ul_debugobj(mn, "kernel event veiled")); + } + return status; +} + /* * kernel monitor operations */ static const struct monitor_opers kernel_opers = { .op_get_fd = kernel_monitor_get_fd, .op_close_fd = kernel_monitor_close_fd, + .op_event_verify = kernel_event_verify }; /** @@ -545,6 +563,28 @@ err: return rc; } +/** + * mnt_monitor_veil_kernel: + * @mn: monitor instance + * @enable: 1 or 0 + * + * Force monitor to ignore kernel events if the same mount/umount operation + * will generate an userspace event later. The kernel-only mount operation will + * be not affected. + * + * Return: 0 on success and <0 on error. + * + * Since: 2.40 + */ +int mnt_monitor_veil_kernel(struct libmnt_monitor *mn, int enable) +{ + if (!mn) + return -EINVAL; + + mn->kernel_veiled = enable ? 1 : 0; + return 0; +} + /* * Add/Remove monitor entry to/from monitor epoll. */ @@ -852,6 +892,8 @@ static struct libmnt_monitor *create_test_monitor(int argc, char *argv[]) warn("failed to initialize kernel monitor"); goto err; } + } else if (strcmp(argv[i], "veil") == 0) { + mnt_monitor_veil_kernel(mn, 1); } } if (i == 1) { @@ -899,12 +941,14 @@ static int __test_epoll(struct libmnt_test *ts __attribute__((unused)), goto done; } - printf("waiting for changes...\n"); do { const char *filename = NULL; struct epoll_event events[1]; - int n = epoll_wait(efd, events, 1, -1); + int n; + + printf("waiting for changes...\n"); + n = epoll_wait(efd, events, 1, -1); if (n < 0) { rc = -errno; warn("polling error"); @@ -962,6 +1006,7 @@ static int test_wait(struct libmnt_test *ts __attribute__((unused)), while (mnt_monitor_next_change(mn, &filename, NULL) == 0) printf(" %s: change detected\n", filename); + printf("waiting for changes...\n"); } mnt_unref_monitor(mn); return 0; @@ -970,9 +1015,9 @@ static int test_wait(struct libmnt_test *ts __attribute__((unused)), int main(int argc, char *argv[]) { struct libmnt_test tss[] = { - { "--epoll", test_epoll, "<userspace kernel ...> monitor in epoll" }, - { "--epoll-clean", test_epoll_cleanup, "<userspace kernel ...> monitor in epoll and clean events" }, - { "--wait", test_wait, "<userspace kernel ...> monitor wait function" }, + { "--epoll", test_epoll, "<userspace kernel veil ...> monitor in epoll" }, + { "--epoll-clean", test_epoll_cleanup, "<userspace kernel veil ...> monitor in epoll and clean events" }, + { "--wait", test_wait, "<userspace kernel veil ...> monitor wait function" }, { NULL } }; |