From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Simmons Date: Thu, 27 Feb 2020 16:15:48 -0500 Subject: [lustre-devel] [PATCH 480/622] lustre: mdc: hold obd while processing changelog In-Reply-To: <1582838290-17243-1-git-send-email-jsimmons@infradead.org> References: <1582838290-17243-1-git-send-email-jsimmons@infradead.org> Message-ID: <1582838290-17243-481-git-send-email-jsimmons@infradead.org> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: lustre-devel@lists.lustre.org From: Hongchao Zhang 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 Reviewed-on: https://review.whamcloud.com/35784 Reviewed-by: Andreas Dilger Reviewed-by: Emoly Liu Reviewed-by: Oleg Drokin Signed-off-by: James Simmons --- 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