#include #include #include "thread_map.h" #include "evsel.h" #include "debug.h" #include "tests.h" int test__openat_syscall_event(int subtest __maybe_unused) { int err = -1, fd; struct perf_evsel *evsel; unsigned int nr_openat_calls = 111, i; struct thread_map *threads = thread_map__new(-1, getpid(), UINT_MAX); char sbuf[STRERR_BUFSIZE]; char errbuf[BUFSIZ]; if (threads == NULL) { pr_debug("thread_map__new\n"); return -1; } evsel = perf_evsel__newtp("syscalls", "sys_enter_openat"); if (IS_ERR(evsel)) { tracing_path__strerror_open_tp(errno, errbuf, sizeof(errbuf), "syscalls", "sys_enter_openat"); pr_debug("%s\n", errbuf); goto out_thread_map_delete; } if (perf_evsel__open_per_thread(evsel, threads) < 0) { pr_debug("failed to open counter: %s, " "tweak /proc/sys/kernel/perf_event_paranoid?\n", str_error_r(errno, sbuf, sizeof(sbuf))); goto out_evsel_delete; } for (i = 0; i < nr_openat_calls; ++i) { fd = openat(0, "/etc/passwd", O_RDONLY); close(fd); } if (perf_evsel__read_on_cpu(evsel, 0, 0) < 0) { pr_debug("perf_evsel__read_on_cpu\n"); goto out_close_fd; } if (perf_counts(evsel->counts, 0, 0)->val != nr_openat_calls) { pr_debug("perf_evsel__read_on_cpu: expected to intercept %d calls, got %" PRIu64 "\n", nr_openat_calls, perf_counts(evsel->counts, 0, 0)->val); goto out_close_fd; } err = 0; out_close_fd: perf_evsel__close_fd(evsel, 1, threads->nr); out_evsel_delete: perf_evsel__delete(evsel); out_thread_map_delete: thread_map__put(threads); return err; } '>refslogtreecommitdiff
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authorChristoph Hellwig <hch@lst.de>2017-01-20 09:31:54 -0800
committerDarrick J. Wong <darrick.wong@oracle.com>2017-01-23 10:55:07 -0800
commitd2b3964a0780d2d2994eba57f950d6c9fe489ed8 (patch)
treee5431a683b41059abd0032aa46685ae78d766a50 /net
parent7a308bb3016f57e5be11a677d15b821536419d36 (diff)
xfs: fix COW writeback race
Due to the way how xfs_iomap_write_allocate tries to convert the whole found extents from delalloc to real space we can run into a race condition with multiple threads doing writes to this same extent. For the non-COW case that is harmless as the only thing that can happen is that we call xfs_bmapi_write on an extent that has already been converted to a real allocation. For COW writes where we move the extent from the COW to the data fork after I/O completion the race is, however, not quite as harmless. In the worst case we are now calling xfs_bmapi_write on a region that contains hole in the COW work, which will trip up an assert in debug builds or lead to file system corruption in non-debug builds. This seems to be reproducible with workloads of small O_DSYNC write, although so far I've not managed to come up with a with an isolated reproducer. The fix for the issue is relatively simple: tell xfs_bmapi_write that we are only asked to convert delayed allocations and skip holes in that case. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
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