Rakesh Pandit
2014-Mar-25 14:47 UTC
[PATCH] Btrfs-progs: scrub: disable thread cancelability during mutex locks
scrub_progress_cycle thread runs in asynchronous type but locks mutex while reading shared data. This patch disables cancelability for a brief time while locks are on so as to make sure they are unlocked before thread is canceled. scrub_write_progress gets called from scrub_progress_cycle in asynchronous thread but cancelability is disabled after mutex is locked. This patch moves the call to set cancelability type before mutex lock and makes corresponding changes to labels for error handling. Signed-off-by: Rakesh Pandit <rakesh@tuxera.com> --- cmds-scrub.c | 31 ++++++++++++++++++++++--------- 1 file changed, 22 insertions(+), 9 deletions(-) diff --git a/cmds-scrub.c b/cmds-scrub.c index d3bd148..4338a0b 100644 --- a/cmds-scrub.c +++ b/cmds-scrub.c @@ -773,31 +773,31 @@ static int scrub_write_progress(pthread_mutex_t *m, const char *fsid, int fd = -1; int old; - ret = pthread_mutex_lock(m); + ret = pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &old); if (ret) { err = -ret; - goto fail; + goto out3; } - ret = pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &old); + ret = pthread_mutex_lock(m); if (ret) { err = -ret; - goto out; + goto out2; } fd = scrub_open_file_w(SCRUB_DATA_FILE, fsid, "tmp"); if (fd < 0) { err = fd; - goto out; + goto out1; } err = scrub_write_file(fd, fsid, data, n); if (err) - goto out; + goto out1; err = scrub_rename_file(SCRUB_DATA_FILE, fsid, "tmp"); if (err) - goto out; + goto out1; -out: +out1: if (fd >= 0) { ret = close(fd); if (ret) @@ -808,11 +808,12 @@ out: if (ret && !err) err = -ret; -fail: +out2: ret = pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, &old); if (ret && !err) err = -ret; +out3: return err; } @@ -944,6 +945,10 @@ static void *scrub_progress_cycle(void *ctx) * result we got for the current write and go * on. flag should be set on next cycle, then. */ + perr = pthread_setcancelstate( + PTHREAD_CANCEL_DISABLE, &old); + if (perr) + goto out; perr = pthread_mutex_lock(&sp_shared->progress_mutex); if (perr) goto out; @@ -952,12 +957,20 @@ static void *scrub_progress_cycle(void *ctx) &sp_shared->progress_mutex); if (perr) goto out; + perr = pthread_setcancelstate( + PTHREAD_CANCEL_ENABLE, &old); + if (perr) + goto out; memcpy(sp, sp_last, sizeof(*sp)); continue; } perr = pthread_mutex_unlock(&sp_shared->progress_mutex); if (perr) goto out; + perr = pthread_setcancelstate( + PTHREAD_CANCEL_ENABLE, &old); + if (perr) + goto out; memcpy(sp, sp_shared, sizeof(*sp)); memcpy(sp_last, sp_shared, sizeof(*sp)); } -- 1.8.5.3 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html