[lustre-devel] [PATCH 480/622] lustre: mdc: hold obd while processing changelog
James Simmons
jsimmons at infradead.org
Thu Feb 27 13:15:48 PST 2020
From: Hongchao Zhang <hongchao at whamcloud.com>
During read/write changelog, the corresponding obd_device should
be held to protect it from being released by umount.
WC-bug-id: https://jira.whamcloud.com/browse/LU-11626
Lustre-commit: d7bb6647cd4d ("LU-11626 mdc: hold obd while processing changelog")
Signed-off-by: Hongchao Zhang <hongchao at whamcloud.com>
Reviewed-on: https://review.whamcloud.com/35784
Reviewed-by: Andreas Dilger <adilger at whamcloud.com>
Reviewed-by: Emoly Liu <emoly at whamcloud.com>
Reviewed-by: Oleg Drokin <green at whamcloud.com>
Signed-off-by: James Simmons <jsimmons at infradead.org>
---
fs/lustre/mdc/mdc_changelog.c | 121 ++++++++++++++++++++++++------------------
1 file changed, 70 insertions(+), 51 deletions(-)
diff --git a/fs/lustre/mdc/mdc_changelog.c b/fs/lustre/mdc/mdc_changelog.c
index 9af0541..043549d 100644
--- a/fs/lustre/mdc/mdc_changelog.c
+++ b/fs/lustre/mdc/mdc_changelog.c
@@ -69,8 +69,10 @@ struct chlg_registered_dev {
};
struct chlg_reader_state {
- /* Device this state is associated with */
- struct chlg_registered_dev *crs_dev;
+ /* Shortcut to the corresponding OBD device */
+ struct obd_device *crs_obd;
+ /* the corresponding chlg_registered_dev */
+ struct chlg_registered_dev *crs_ced;
/* Producer thread (if any) */
struct task_struct *crs_prod_task;
/* An error occurred that prevents from reading further */
@@ -109,6 +111,41 @@ enum {
};
/**
+ * Deregister a changelog character device whose refcount has reached zero.
+ */
+static void chlg_dev_clear(struct kref *kref)
+{
+ struct chlg_registered_dev *entry = container_of(kref,
+ struct chlg_registered_dev,
+ ced_refs);
+
+ list_del(&entry->ced_link);
+ misc_deregister(&entry->ced_misc);
+ kfree(entry);
+}
+
+static inline struct obd_device *chlg_obd_get(struct chlg_registered_dev *dev)
+{
+ struct obd_device *obd;
+
+ mutex_lock(&chlg_registered_dev_lock);
+ if (list_empty(&dev->ced_obds))
+ return NULL;
+
+ obd = list_first_entry(&dev->ced_obds, struct obd_device,
+ u.cli.cl_chg_dev_linkage);
+ class_incref(obd, "changelog", dev);
+ mutex_unlock(&chlg_registered_dev_lock);
+ return obd;
+}
+
+static inline void chlg_obd_put(struct chlg_registered_dev *dev,
+ struct obd_device *obd)
+{
+ class_decref(obd, "changelog", dev);
+}
+
+/**
* ChangeLog catalog processing callback invoked on each record.
* If the current record is eligible to userland delivery, push
* it into the crs_rec_queue where the consumer code will fetch it.
@@ -142,7 +179,7 @@ static int chlg_read_cat_process_cb(const struct lu_env *env,
if (rec->cr_hdr.lrh_type != CHANGELOG_REC) {
rc = -EINVAL;
CERROR("%s: not a changelog rec %x/%d in llog : rc = %d\n",
- crs->crs_dev->ced_name, rec->cr_hdr.lrh_type,
+ crs->crs_obd->obd_name, rec->cr_hdr.lrh_type,
rec->cr.cr_type, rc);
return rc;
}
@@ -193,17 +230,6 @@ static void enq_record_delete(struct chlg_rec_entry *rec)
kfree(rec);
}
-/*
- * Find any OBD device associated with this reader
- * chlg_registered_dev_lock is held.
- */
-static inline struct obd_device *chlg_obd_get(struct chlg_registered_dev *dev)
-{
- return list_first_entry_or_null(&dev->ced_obds,
- struct obd_device,
- u.cli.cl_chg_dev_linkage);
-}
-
/**
* Record prefetch thread entry point. Opens the changelog catalog and starts
* reading records.
@@ -215,27 +241,28 @@ static inline struct obd_device *chlg_obd_get(struct chlg_registered_dev *dev)
static int chlg_load(void *args)
{
struct chlg_reader_state *crs = args;
+ struct chlg_registered_dev *ced = crs->crs_ced;
struct obd_device *obd;
struct llog_ctxt *ctx = NULL;
struct llog_handle *llh = NULL;
int rc;
- mutex_lock(&chlg_registered_dev_lock);
- obd = chlg_obd_get(crs->crs_dev);
- if (!obd) {
- rc = -ENOENT;
- goto err_out;
- }
+ crs->crs_last_catidx = -1;
+ crs->crs_last_idx = 0;
+
+again:
+ obd = chlg_obd_get(ced);
+ if (!obd)
+ return -ENODEV;
+
+ crs->crs_obd = obd;
+
ctx = llog_get_context(obd, LLOG_CHANGELOG_REPL_CTXT);
if (!ctx) {
rc = -ENOENT;
goto err_out;
}
- crs->crs_last_catidx = -1;
- crs->crs_last_idx = 0;
-
-again:
rc = llog_open(NULL, ctx, &llh, NULL, CHANGELOG_CATALOG,
LLOG_OPEN_EXISTS);
if (rc) {
@@ -268,6 +295,8 @@ static int chlg_load(void *args)
}
if (!kthread_should_stop() && crs->crs_poll) {
llog_cat_close(NULL, llh);
+ llog_ctxt_put(ctx);
+ class_decref(obd, "changelog", crs);
schedule_timeout_interruptible(HZ);
goto again;
}
@@ -275,7 +304,6 @@ static int chlg_load(void *args)
crs->crs_eof = true;
err_out:
- mutex_unlock(&chlg_registered_dev_lock);
if (rc < 0)
crs->crs_err = rc;
@@ -287,6 +315,8 @@ static int chlg_load(void *args)
if (ctx)
llog_ctxt_put(ctx);
+ crs->crs_obd = NULL;
+ chlg_obd_put(ced, obd);
wait_event_idle(crs->crs_waitq_prod, kthread_should_stop());
return rc;
@@ -454,19 +484,19 @@ static int chlg_clear(struct chlg_reader_state *crs, u32 reader, u64 record)
.cs_recno = record,
.cs_id = reader
};
- int ret;
+ int rc;
- mutex_lock(&chlg_registered_dev_lock);
- obd = chlg_obd_get(crs->crs_dev);
+ obd = chlg_obd_get(crs->crs_ced);
if (!obd)
- ret = -ENOENT;
- else
- ret = obd_set_info_async(NULL, obd->obd_self_export,
- strlen(KEY_CHANGELOG_CLEAR),
- KEY_CHANGELOG_CLEAR, sizeof(cs),
- &cs, NULL);
- mutex_unlock(&chlg_registered_dev_lock);
- return ret;
+ return -ENODEV;
+
+ rc = obd_set_info_async(NULL, obd->obd_self_export,
+ strlen(KEY_CHANGELOG_CLEAR),
+ KEY_CHANGELOG_CLEAR, sizeof(cs),
+ &cs, NULL);
+ chlg_obd_put(crs->crs_ced, obd);
+
+ return rc;
}
/** Maximum changelog control command size */
@@ -540,7 +570,8 @@ static int chlg_open(struct inode *inode, struct file *file)
if (!crs)
return -ENOMEM;
- crs->crs_dev = dev;
+ kref_get(&dev->ced_refs);
+ crs->crs_ced = dev;
crs->crs_err = false;
crs->crs_eof = false;
@@ -564,6 +595,7 @@ static int chlg_open(struct inode *inode, struct file *file)
return 0;
err_crs:
+ kref_put(&dev->ced_refs, chlg_dev_clear);
kfree(crs);
return rc;
}
@@ -589,6 +621,7 @@ static int chlg_release(struct inode *inode, struct file *file)
list_for_each_entry_safe(rec, tmp, &crs->crs_rec_queue, enq_linkage)
enq_record_delete(rec);
+ kref_put(&crs->crs_ced->ced_refs, chlg_dev_clear);
kfree(crs);
return rc;
}
@@ -763,20 +796,6 @@ int mdc_changelog_cdev_init(struct obd_device *obd)
}
/**
- * Deregister a changelog character device whose refcount has reached zero.
- */
-static void chlg_dev_clear(struct kref *kref)
-{
- struct chlg_registered_dev *entry = container_of(kref,
- struct chlg_registered_dev,
- ced_refs);
- LASSERT(mutex_is_locked(&chlg_registered_dev_lock));
- list_del(&entry->ced_link);
- misc_deregister(&entry->ced_misc);
- kfree(entry);
-}
-
-/**
* Release OBD, decrease reference count of the corresponding changelog device.
*/
void mdc_changelog_cdev_finish(struct obd_device *obd)
--
1.8.3.1
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