gfs2: Don't withdraw under a spin lock

In two places, the gfs2_io_error_bh macro is called while holding the
sd_ail_lock spin lock.  This isn't allowed because gfs2_io_error_bh
withdraws the filesystem, which can sleep because it issues a uevent.
To fix that, add a gfs2_io_error_bh_wd macro that does withdraw the
filesystem and change gfs2_io_error_bh to not withdraw the filesystem.
In those places where the new gfs2_io_error_bh is used, withdraw the
filesystem after releasing sd_ail_lock.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Reviewed-by: Andrew Price <anprice@redhat.com>

5 files changed, 49 insertions, 31 deletions

diff --git a/fs/gfs2/log.c b/fs/gfs2/log.c
index 0248835625f1..a767fad02386 100644
--- a/fs/gfs2/log.c
+++ b/fs/gfs2/log.c
@@ -92,7 +92,8 @@ static void gfs2_remove_from_ail(struct gfs2_bufdata *bd)
 
 static int gfs2_ail1_start_one(struct gfs2_sbd *sdp,
                                struct writeback_control *wbc,
-                               struct gfs2_trans *tr)
+                               struct gfs2_trans *tr,
+                               bool *withdraw)
 __releases(&sdp->sd_ail_lock)
 __acquires(&sdp->sd_ail_lock)
 {
@@ -107,8 +108,10 @@ __acquires(&sdp->sd_ail_lock)
                 gfs2_assert(sdp, bd->bd_tr == tr);
 
                 if (!buffer_busy(bh)) {
-                        if (!buffer_uptodate(bh))
+                        if (!buffer_uptodate(bh)) {
                                 gfs2_io_error_bh(sdp, bh);
+                                *withdraw = true;
+                        }
                         list_move(&bd->bd_ail_st_list, &tr->tr_ail2_list);
                         continue;
                 }
@@ -148,6 +151,7 @@ void gfs2_ail1_flush(struct gfs2_sbd *sdp, struct writeback_control *wbc)
         struct list_head *head = &sdp->sd_ail1_list;
         struct gfs2_trans *tr;
         struct blk_plug plug;
+        bool withdraw = false;
 
         trace_gfs2_ail_flush(sdp, wbc, 1);
         blk_start_plug(&plug);
@@ -156,11 +160,13 @@ restart:
         list_for_each_entry_reverse(tr, head, tr_list) {
                 if (wbc->nr_to_write <= 0)
                         break;
-                if (gfs2_ail1_start_one(sdp, wbc, tr))
+                if (gfs2_ail1_start_one(sdp, wbc, tr, &withdraw))
                         goto restart;
         }
         spin_unlock(&sdp->sd_ail_lock);
         blk_finish_plug(&plug);
+        if (withdraw)
+                gfs2_lm_withdraw(sdp, NULL);
         trace_gfs2_ail_flush(sdp, wbc, 0);
 }
 
@@ -188,7 +194,8 @@ static void gfs2_ail1_start(struct gfs2_sbd *sdp)
  *
  */
 
-static void gfs2_ail1_empty_one(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
+static void gfs2_ail1_empty_one(struct gfs2_sbd *sdp, struct gfs2_trans *tr,
+                                bool *withdraw)
 {
         struct gfs2_bufdata *bd, *s;
         struct buffer_head *bh;
@@ -199,11 +206,12 @@ static void gfs2_ail1_empty_one(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
                 gfs2_assert(sdp, bd->bd_tr == tr);
                 if (buffer_busy(bh))
                         continue;
-                if (!buffer_uptodate(bh))
+                if (!buffer_uptodate(bh)) {
                         gfs2_io_error_bh(sdp, bh);
+                        *withdraw = true;
+                }
                 list_move(&bd->bd_ail_st_list, &tr->tr_ail2_list);
         }
-
 }
 
 /**
@@ -218,10 +226,11 @@ static int gfs2_ail1_empty(struct gfs2_sbd *sdp)
         struct gfs2_trans *tr, *s;
         int oldest_tr = 1;
         int ret;
+        bool withdraw = false;
 
         spin_lock(&sdp->sd_ail_lock);
         list_for_each_entry_safe_reverse(tr, s, &sdp->sd_ail1_list, tr_list) {
-                gfs2_ail1_empty_one(sdp, tr);
+                gfs2_ail1_empty_one(sdp, tr, &withdraw);
                 if (list_empty(&tr->tr_ail1_list) && oldest_tr)
                         list_move(&tr->tr_list, &sdp->sd_ail2_list);
                 else
@@ -230,6 +239,9 @@ static int gfs2_ail1_empty(struct gfs2_sbd *sdp)
         ret = list_empty(&sdp->sd_ail1_list);
         spin_unlock(&sdp->sd_ail_lock);
 
+        if (withdraw)
+                gfs2_lm_withdraw(sdp, "fatal: I/O error(s)\n");
+
         return ret;
 }
 
diff --git a/fs/gfs2/lops.c b/fs/gfs2/lops.c
index 4d6567990baf..f2567f958d00 100644
--- a/fs/gfs2/lops.c
+++ b/fs/gfs2/lops.c
@@ -49,7 +49,7 @@ void gfs2_pin(struct gfs2_sbd *sdp, struct buffer_head *bh)
         if (test_set_buffer_pinned(bh))
                 gfs2_assert_withdraw(sdp, 0);
         if (!buffer_uptodate(bh))
-                gfs2_io_error_bh(sdp, bh);
+                gfs2_io_error_bh_wd(sdp, bh);
         bd = bh->b_private;
         /* If this buffer is in the AIL and it has already been written
          * to in-place disk block, remove it from the AIL.
diff --git a/fs/gfs2/meta_io.c b/fs/gfs2/meta_io.c
index 52de1036d9f9..be9c0bf697fe 100644
--- a/fs/gfs2/meta_io.c
+++ b/fs/gfs2/meta_io.c
@@ -293,7 +293,7 @@ int gfs2_meta_read(struct gfs2_glock *gl, u64 blkno, int flags,
         if (unlikely(!buffer_uptodate(bh))) {
                 struct gfs2_trans *tr = current->journal_info;
                 if (tr && test_bit(TR_TOUCHED, &tr->tr_flags))
-                        gfs2_io_error_bh(sdp, bh);
+                        gfs2_io_error_bh_wd(sdp, bh);
                 brelse(bh);
                 *bhp = NULL;
                 return -EIO;
@@ -320,7 +320,7 @@ int gfs2_meta_wait(struct gfs2_sbd *sdp, struct buffer_head *bh)
         if (!buffer_uptodate(bh)) {
                 struct gfs2_trans *tr = current->journal_info;
                 if (tr && test_bit(TR_TOUCHED, &tr->tr_flags))
-                        gfs2_io_error_bh(sdp, bh);
+                        gfs2_io_error_bh_wd(sdp, bh);
                 return -EIO;
         }
         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
diff --git a/fs/gfs2/util.c b/fs/gfs2/util.c
index 763d659db91b..59c811de0dc7 100644
--- a/fs/gfs2/util.c
+++ b/fs/gfs2/util.c
@@ -46,14 +46,16 @@ int gfs2_lm_withdraw(struct gfs2_sbd *sdp, const char *fmt, ...)
             test_and_set_bit(SDF_SHUTDOWN, &sdp->sd_flags))
                 return 0;
 
-        va_start(args, fmt);
+        if (fmt) {
+                va_start(args, fmt);
 
-        vaf.fmt = fmt;
-        vaf.va = &args;
+                vaf.fmt = fmt;
+                vaf.va = &args;
 
-        fs_err(sdp, "%pV", &vaf);
+                fs_err(sdp, "%pV", &vaf);
 
-        va_end(args);
+                va_end(args);
+        }
 
         if (sdp->sd_args.ar_errors == GFS2_ERRORS_WITHDRAW) {
                 fs_err(sdp, "about to withdraw this file system\n");
@@ -246,21 +248,21 @@ int gfs2_io_error_i(struct gfs2_sbd *sdp, const char *function, char *file,
 }
 
 /**
- * gfs2_io_error_bh_i - Flag a buffer I/O error and withdraw
- * Returns: -1 if this call withdrew the machine,
- *          0 if it was already withdrawn
+ * gfs2_io_error_bh_i - Flag a buffer I/O error
+ * @withdraw: withdraw the filesystem
  */
 
-int gfs2_io_error_bh_i(struct gfs2_sbd *sdp, struct buffer_head *bh,
-                       const char *function, char *file, unsigned int line)
+void gfs2_io_error_bh_i(struct gfs2_sbd *sdp, struct buffer_head *bh,
+                        const char *function, char *file, unsigned int line,
+                        bool withdraw)
 {
-        int rv;
-        rv = gfs2_lm_withdraw(sdp,
-                              "fatal: I/O error\n"
-                              "  block = %llu\n"
-                              "  function = %s, file = %s, line = %u\n",
-                              (unsigned long long)bh->b_blocknr,
-                              function, file, line);
-        return rv;
+        fs_err(sdp,
+               "fatal: I/O error\n"
+               "  block = %llu\n"
+               "  function = %s, file = %s, line = %u\n",
+               (unsigned long long)bh->b_blocknr,
+               function, file, line);
+        if (withdraw)
+                gfs2_lm_withdraw(sdp, NULL);
 }
 
diff --git a/fs/gfs2/util.h b/fs/gfs2/util.h
index 3926f95a6eb7..96ac4aba4738 100644
--- a/fs/gfs2/util.h
+++ b/fs/gfs2/util.h
@@ -136,11 +136,15 @@ int gfs2_io_error_i(struct gfs2_sbd *sdp, const char *function,
 gfs2_io_error_i((sdp), __func__, __FILE__, __LINE__);
 
 
-int gfs2_io_error_bh_i(struct gfs2_sbd *sdp, struct buffer_head *bh,
-                       const char *function, char *file, unsigned int line);
+void gfs2_io_error_bh_i(struct gfs2_sbd *sdp, struct buffer_head *bh,
+                        const char *function, char *file, unsigned int line,
+                        bool withdraw);
+
+#define gfs2_io_error_bh_wd(sdp, bh) \
+gfs2_io_error_bh_i((sdp), (bh), __func__, __FILE__, __LINE__, true);
 
 #define gfs2_io_error_bh(sdp, bh) \
-gfs2_io_error_bh_i((sdp), (bh), __func__, __FILE__, __LINE__);
+gfs2_io_error_bh_i((sdp), (bh), __func__, __FILE__, __LINE__, false);
 
 
 extern struct kmem_cache *gfs2_glock_cachep;