* [PATCH 1/3] xfs_scrub: refactor queueing of subdir scan work item
2019-09-25 21:31 [PATCH 0/3] xfs_scrub: fix bugs in vfs tree walk code Darrick J. Wong
@ 2019-09-25 21:31 ` Darrick J. Wong
2019-09-25 21:31 ` [PATCH 2/3] xfs_scrub: fix nr_dirs accounting problems Darrick J. Wong
2019-09-25 21:31 ` [PATCH 3/3] xfs_scrub: remove unnecessary wakeup wait in scan_fs_tree Darrick J. Wong
2 siblings, 0 replies; 6+ messages in thread
From: Darrick J. Wong @ 2019-09-25 21:31 UTC (permalink / raw)
To: sandeen, darrick.wong; +Cc: linux-xfs, Dave Chinner
From: Darrick J. Wong <darrick.wong@oracle.com>
Replace the open-coded process of queueing a subdirectory for scanning
with a single helper function.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
---
scrub/vfs.c | 109 ++++++++++++++++++++++++++++++++++++-----------------------
1 file changed, 67 insertions(+), 42 deletions(-)
diff --git a/scrub/vfs.c b/scrub/vfs.c
index b5d54837..add4e815 100644
--- a/scrub/vfs.c
+++ b/scrub/vfs.c
@@ -43,6 +43,57 @@ struct scan_fs_tree_dir {
bool rootdir;
};
+static void scan_fs_dir(struct workqueue *wq, xfs_agnumber_t agno, void *arg);
+
+/* Queue a directory for scanning. */
+static bool
+queue_subdir(
+ struct scrub_ctx *ctx,
+ struct scan_fs_tree *sft,
+ struct workqueue *wq,
+ const char *path,
+ bool is_rootdir)
+{
+ struct scan_fs_tree_dir *new_sftd;
+ int error;
+
+ new_sftd = malloc(sizeof(struct scan_fs_tree_dir));
+ if (!new_sftd) {
+ str_errno(ctx, _("creating directory scan context"));
+ return false;
+ }
+
+ new_sftd->path = strdup(path);
+ if (!new_sftd->path) {
+ str_errno(ctx, _("creating directory scan path"));
+ goto out_sftd;
+ }
+
+ new_sftd->sft = sft;
+ new_sftd->rootdir = is_rootdir;
+
+ pthread_mutex_lock(&sft->lock);
+ sft->nr_dirs++;
+ pthread_mutex_unlock(&sft->lock);
+ error = workqueue_add(wq, scan_fs_dir, 0, new_sftd);
+ if (error) {
+ /*
+ * XXX: need to decrement nr_dirs here; will do that in the
+ * next patch.
+ */
+ str_info(ctx, ctx->mntpoint,
+_("Could not queue subdirectory scan work."));
+ goto out_path;
+ }
+
+ return true;
+out_path:
+ free(new_sftd->path);
+out_sftd:
+ free(new_sftd);
+ return false;
+}
+
/* Scan a directory sub tree. */
static void
scan_fs_dir(
@@ -56,7 +107,6 @@ scan_fs_dir(
DIR *dir;
struct dirent *dirent;
char newpath[PATH_MAX];
- struct scan_fs_tree_dir *new_sftd;
struct stat sb;
int dir_fd;
int error;
@@ -117,25 +167,10 @@ scan_fs_dir(
/* If directory, call ourselves recursively. */
if (S_ISDIR(sb.st_mode) && strcmp(".", dirent->d_name) &&
strcmp("..", dirent->d_name)) {
- new_sftd = malloc(sizeof(struct scan_fs_tree_dir));
- if (!new_sftd) {
- str_errno(ctx, newpath);
- sft->moveon = false;
- break;
- }
- new_sftd->path = strdup(newpath);
- new_sftd->sft = sft;
- new_sftd->rootdir = false;
- pthread_mutex_lock(&sft->lock);
- sft->nr_dirs++;
- pthread_mutex_unlock(&sft->lock);
- error = workqueue_add(wq, scan_fs_dir, 0, new_sftd);
- if (error) {
- str_info(ctx, ctx->mntpoint,
-_("Could not queue subdirectory scan work."));
- sft->moveon = false;
+ sft->moveon = queue_subdir(ctx, sft, wq, newpath,
+ false);
+ if (!sft->moveon)
break;
- }
}
}
@@ -165,11 +200,10 @@ scan_fs_tree(
{
struct workqueue wq;
struct scan_fs_tree sft;
- struct scan_fs_tree_dir *sftd;
int ret;
sft.moveon = true;
- sft.nr_dirs = 1;
+ sft.nr_dirs = 0;
sft.root_sb = ctx->mnt_sb;
sft.dir_fn = dir_fn;
sft.dirent_fn = dirent_fn;
@@ -177,41 +211,32 @@ scan_fs_tree(
pthread_mutex_init(&sft.lock, NULL);
pthread_cond_init(&sft.wakeup, NULL);
- sftd = malloc(sizeof(struct scan_fs_tree_dir));
- if (!sftd) {
- str_errno(ctx, ctx->mntpoint);
- return false;
- }
- sftd->path = strdup(ctx->mntpoint);
- sftd->sft = &sft;
- sftd->rootdir = true;
-
ret = workqueue_create(&wq, (struct xfs_mount *)ctx,
scrub_nproc_workqueue(ctx));
if (ret) {
str_info(ctx, ctx->mntpoint, _("Could not create workqueue."));
- goto out_free;
+ return false;
}
- ret = workqueue_add(&wq, scan_fs_dir, 0, sftd);
- if (ret) {
- str_info(ctx, ctx->mntpoint,
-_("Could not queue directory scan work."));
+
+ sft.moveon = queue_subdir(ctx, &sft, &wq, ctx->mntpoint, true);
+ if (!sft.moveon)
goto out_wq;
- }
+ /*
+ * Wait for the wakeup to trigger, which should only happen when the
+ * last worker thread decrements nr_dirs to zero. Once the worker
+ * triggers the wakeup and unlocks the sft lock, it's no longer safe
+ * for any worker thread to access sft, as we now own the lock and are
+ * about to tear everything down.
+ */
pthread_mutex_lock(&sft.lock);
pthread_cond_wait(&sft.wakeup, &sft.lock);
assert(sft.nr_dirs == 0);
pthread_mutex_unlock(&sft.lock);
- workqueue_destroy(&wq);
- return sft.moveon;
out_wq:
workqueue_destroy(&wq);
-out_free:
- free(sftd->path);
- free(sftd);
- return false;
+ return sft.moveon;
}
#ifndef FITRIM
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH 2/3] xfs_scrub: fix nr_dirs accounting problems
2019-09-25 21:31 [PATCH 0/3] xfs_scrub: fix bugs in vfs tree walk code Darrick J. Wong
2019-09-25 21:31 ` [PATCH 1/3] xfs_scrub: refactor queueing of subdir scan work item Darrick J. Wong
@ 2019-09-25 21:31 ` Darrick J. Wong
2019-09-25 21:31 ` [PATCH 3/3] xfs_scrub: remove unnecessary wakeup wait in scan_fs_tree Darrick J. Wong
2 siblings, 0 replies; 6+ messages in thread
From: Darrick J. Wong @ 2019-09-25 21:31 UTC (permalink / raw)
To: sandeen, darrick.wong; +Cc: linux-xfs, Dave Chinner
From: Darrick J. Wong <darrick.wong@oracle.com>
When we're scanning the directory tree, we bump nr_dirs every time we
think we're going to queue a new directory to process, and we decrement
it every time we're finished doing something with a directory
(successful or not). We forgot to undo a counter increment when
workqueue_add fails, so refactor the code into helpers and call them
as necessary for correct operation.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
---
scrub/vfs.c | 42 +++++++++++++++++++++++++++++-------------
1 file changed, 29 insertions(+), 13 deletions(-)
diff --git a/scrub/vfs.c b/scrub/vfs.c
index add4e815..f8bc98c0 100644
--- a/scrub/vfs.c
+++ b/scrub/vfs.c
@@ -45,6 +45,32 @@ struct scan_fs_tree_dir {
static void scan_fs_dir(struct workqueue *wq, xfs_agnumber_t agno, void *arg);
+/* Increment the number of directories that are queued for processing. */
+static void
+inc_nr_dirs(
+ struct scan_fs_tree *sft)
+{
+ pthread_mutex_lock(&sft->lock);
+ sft->nr_dirs++;
+ pthread_mutex_unlock(&sft->lock);
+}
+
+/*
+ * Decrement the number of directories that are queued for processing and if
+ * we ran out of dirs to process, wake up anyone who was waiting for processing
+ * to finish.
+ */
+static void
+dec_nr_dirs(
+ struct scan_fs_tree *sft)
+{
+ pthread_mutex_lock(&sft->lock);
+ sft->nr_dirs--;
+ if (sft->nr_dirs == 0)
+ pthread_cond_signal(&sft->wakeup);
+ pthread_mutex_unlock(&sft->lock);
+}
+
/* Queue a directory for scanning. */
static bool
queue_subdir(
@@ -72,15 +98,10 @@ queue_subdir(
new_sftd->sft = sft;
new_sftd->rootdir = is_rootdir;
- pthread_mutex_lock(&sft->lock);
- sft->nr_dirs++;
- pthread_mutex_unlock(&sft->lock);
+ inc_nr_dirs(sft);
error = workqueue_add(wq, scan_fs_dir, 0, new_sftd);
if (error) {
- /*
- * XXX: need to decrement nr_dirs here; will do that in the
- * next patch.
- */
+ dec_nr_dirs(sft);
str_info(ctx, ctx->mntpoint,
_("Could not queue subdirectory scan work."));
goto out_path;
@@ -180,12 +201,7 @@ scan_fs_dir(
str_errno(ctx, sftd->path);
out:
- pthread_mutex_lock(&sft->lock);
- sft->nr_dirs--;
- if (sft->nr_dirs == 0)
- pthread_cond_signal(&sft->wakeup);
- pthread_mutex_unlock(&sft->lock);
-
+ dec_nr_dirs(sft);
free(sftd->path);
free(sftd);
}
^ permalink raw reply related [flat|nested] 6+ messages in thread