Merge branch 'for-linus' of git://git.kernel.dk/linux-block

Pull block layer fixes from Jens Axboe:
 "A small collection of fixes for the current series. It contains:

   - A fix for a use-after-free of a request in blk-mq.  From Ming Lei

   - A fix for a blk-mq bug that could attempt to dereference a NULL rq
     if allocation failed

   - Two xen-blkfront small fixes

   - Cleanup of submit_bio_wait() type uses in the kernel, unifying
     that.  From Kent

   - A fix for 32-bit blkg_rwstat reading.  I apologize for this one
     looking mangled in the shortlog, it's entirely my fault for missing
     an empty line between the description and body of the text"

* 'for-linus' of git://git.kernel.dk/linux-block:
  blk-mq: fix use-after-free of request
  blk-mq: fix dereference of rq->mq_ctx if allocation fails
  block: xen-blkfront: Fix possible NULL ptr dereference
  xen-blkfront: Silence pfn maybe-uninitialized warning
  block: submit_bio_wait() conversions
  Update of blkg_stat and blkg_rwstat may happen in bh context

11 files changed, 44 insertions, 127 deletions

diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
index 1610b22edf09..86154eab9523 100644
--- a/block/blk-cgroup.h
+++ b/block/blk-cgroup.h
@@ -435,9 +435,9 @@ static inline uint64_t blkg_stat_read(struct blkg_stat *stat)
         uint64_t v;
 
         do {
-                start = u64_stats_fetch_begin(&stat->syncp);
+                start = u64_stats_fetch_begin_bh(&stat->syncp);
                 v = stat->cnt;
-        } while (u64_stats_fetch_retry(&stat->syncp, start));
+        } while (u64_stats_fetch_retry_bh(&stat->syncp, start));
 
         return v;
 }
@@ -508,9 +508,9 @@ static inline struct blkg_rwstat blkg_rwstat_read(struct blkg_rwstat *rwstat)
         struct blkg_rwstat tmp;
 
         do {
-                start = u64_stats_fetch_begin(&rwstat->syncp);
+                start = u64_stats_fetch_begin_bh(&rwstat->syncp);
                 tmp = *rwstat;
-        } while (u64_stats_fetch_retry(&rwstat->syncp, start));
+        } while (u64_stats_fetch_retry_bh(&rwstat->syncp, start));
 
         return tmp;
 }
diff --git a/block/blk-flush.c b/block/blk-flush.c
index 331e627301ea..fb6f3c0ffa49 100644
--- a/block/blk-flush.c
+++ b/block/blk-flush.c
@@ -502,15 +502,6 @@ void blk_abort_flushes(struct request_queue *q)
         }
 }
 
-static void bio_end_flush(struct bio *bio, int err)
-{
-        if (err)
-                clear_bit(BIO_UPTODATE, &bio->bi_flags);
-        if (bio->bi_private)
-                complete(bio->bi_private);
-        bio_put(bio);
-}
-
 /**
  * blkdev_issue_flush - queue a flush
  * @bdev:       blockdev to issue flush for
@@ -526,7 +517,6 @@ static void bio_end_flush(struct bio *bio, int err)
 int blkdev_issue_flush(struct block_device *bdev, gfp_t gfp_mask,
                 sector_t *error_sector)
 {
-        DECLARE_COMPLETION_ONSTACK(wait);
         struct request_queue *q;
         struct bio *bio;
         int ret = 0;
@@ -548,13 +538,9 @@ int blkdev_issue_flush(struct block_device *bdev, gfp_t gfp_mask,
                 return -ENXIO;
 
         bio = bio_alloc(gfp_mask, 0);
-        bio->bi_end_io = bio_end_flush;
         bio->bi_bdev = bdev;
-        bio->bi_private = &wait;
 
-        bio_get(bio);
-        submit_bio(WRITE_FLUSH, bio);
-        wait_for_completion_io(&wait);
+        ret = submit_bio_wait(WRITE_FLUSH, bio);
 
         /*
          * The driver must store the error location in ->bi_sector, if
@@ -564,9 +550,6 @@ int blkdev_issue_flush(struct block_device *bdev, gfp_t gfp_mask,
         if (error_sector)
                 *error_sector = bio->bi_sector;
 
-        if (!bio_flagged(bio, BIO_UPTODATE))
-                ret = -EIO;
-
         bio_put(bio);
         return ret;
 }
diff --git a/block/blk-mq.c b/block/blk-mq.c
index cdc629cf075b..c79126e11030 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -202,10 +202,12 @@ static struct request *blk_mq_alloc_request_pinned(struct request_queue *q,
                 if (rq) {
                         blk_mq_rq_ctx_init(q, ctx, rq, rw);
                         break;
-                } else if (!(gfp & __GFP_WAIT))
-                        break;
+                }
 
                 blk_mq_put_ctx(ctx);
+                if (!(gfp & __GFP_WAIT))
+                        break;
+
                 __blk_mq_run_hw_queue(hctx);
                 blk_mq_wait_for_tags(hctx->tags);
         } while (1);
@@ -222,7 +224,8 @@ struct request *blk_mq_alloc_request(struct request_queue *q, int rw,
                 return NULL;
 
         rq = blk_mq_alloc_request_pinned(q, rw, gfp, reserved);
-        blk_mq_put_ctx(rq->mq_ctx);
+        if (rq)
+                blk_mq_put_ctx(rq->mq_ctx);
         return rq;
 }
 
@@ -235,7 +238,8 @@ struct request *blk_mq_alloc_reserved_request(struct request_queue *q, int rw,
                 return NULL;
 
         rq = blk_mq_alloc_request_pinned(q, rw, gfp, true);
-        blk_mq_put_ctx(rq->mq_ctx);
+        if (rq)
+                blk_mq_put_ctx(rq->mq_ctx);
         return rq;
 }
 EXPORT_SYMBOL(blk_mq_alloc_reserved_request);
@@ -308,12 +312,12 @@ void blk_mq_complete_request(struct request *rq, int error)
 
         blk_account_io_completion(rq, bytes);
 
+        blk_account_io_done(rq);
+
         if (rq->end_io)
                 rq->end_io(rq, error);
         else
                 blk_mq_free_request(rq);
-
-        blk_account_io_done(rq);
 }
 
 void __blk_mq_end_io(struct request *rq, int error)
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 432db1b59b00..c4a4c9006288 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -489,7 +489,7 @@ static int blkif_queue_request(struct request *req)
 
                         if ((ring_req->operation == BLKIF_OP_INDIRECT) &&
                             (i % SEGS_PER_INDIRECT_FRAME == 0)) {
-                                unsigned long pfn;
+                                unsigned long uninitialized_var(pfn);
 
                                 if (segments)
                                         kunmap_atomic(segments);
@@ -2011,6 +2011,10 @@ static void blkif_release(struct gendisk *disk, fmode_t mode)
 
         bdev = bdget_disk(disk, 0);
 
+        if (!bdev) {
+                WARN(1, "Block device %s yanked out from us!\n", disk->disk_name);
+                goto out_mutex;
+        }
         if (bdev->bd_openers)
                 goto out;
 
@@ -2041,6 +2045,7 @@ static void blkif_release(struct gendisk *disk, fmode_t mode)
 
 out:
         bdput(bdev);
+out_mutex:
         mutex_unlock(&blkfront_mutex);
 }
 
diff --git a/drivers/md/md.c b/drivers/md/md.c
index e60cebf3f519..21f4d7ff0da2 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -776,16 +776,10 @@ void md_super_wait(struct mddev *mddev)
         finish_wait(&mddev->sb_wait, &wq);
 }
 
-static void bi_complete(struct bio *bio, int error)
-{
-        complete((struct completion*)bio->bi_private);
-}
-
 int sync_page_io(struct md_rdev *rdev, sector_t sector, int size,
                  struct page *page, int rw, bool metadata_op)
 {
         struct bio *bio = bio_alloc_mddev(GFP_NOIO, 1, rdev->mddev);
-        struct completion event;
         int ret;
 
         rw |= REQ_SYNC;
@@ -801,11 +795,7 @@ int sync_page_io(struct md_rdev *rdev, sector_t sector, int size,
         else
                 bio->bi_sector = sector + rdev->data_offset;
         bio_add_page(bio, page, size, 0);
-        init_completion(&event);
-        bio->bi_private = &event;
-        bio->bi_end_io = bi_complete;
-        submit_bio(rw, bio);
-        wait_for_completion(&event);
+        submit_bio_wait(rw, bio);
 
         ret = test_bit(BIO_UPTODATE, &bio->bi_flags);
         bio_put(bio);
diff --git a/fs/btrfs/check-integrity.c b/fs/btrfs/check-integrity.c
index b50764bef141..131d82800b3a 100644
--- a/fs/btrfs/check-integrity.c
+++ b/fs/btrfs/check-integrity.c
@@ -333,7 +333,6 @@ static void btrfsic_release_block_ctx(struct btrfsic_block_data_ctx *block_ctx);
 static int btrfsic_read_block(struct btrfsic_state *state,
                               struct btrfsic_block_data_ctx *block_ctx);
 static void btrfsic_dump_database(struct btrfsic_state *state);
-static void btrfsic_complete_bio_end_io(struct bio *bio, int err);
 static int btrfsic_test_for_metadata(struct btrfsic_state *state,
                                      char **datav, unsigned int num_pages);
 static void btrfsic_process_written_block(struct btrfsic_dev_state *dev_state,
@@ -1687,7 +1686,6 @@ static int btrfsic_read_block(struct btrfsic_state *state,
         for (i = 0; i < num_pages;) {
                 struct bio *bio;
                 unsigned int j;
-                DECLARE_COMPLETION_ONSTACK(complete);
 
                 bio = btrfs_io_bio_alloc(GFP_NOFS, num_pages - i);
                 if (!bio) {
@@ -1698,8 +1696,6 @@ static int btrfsic_read_block(struct btrfsic_state *state,
                 }
                 bio->bi_bdev = block_ctx->dev->bdev;
                 bio->bi_sector = dev_bytenr >> 9;
-                bio->bi_end_io = btrfsic_complete_bio_end_io;
-                bio->bi_private = &complete;
 
                 for (j = i; j < num_pages; j++) {
                         ret = bio_add_page(bio, block_ctx->pagev[j],
@@ -1712,12 +1708,7 @@ static int btrfsic_read_block(struct btrfsic_state *state,
                                "btrfsic: error, failed to add a single page!\n");
                         return -1;
                 }
-                submit_bio(READ, bio);
-
-                /* this will also unplug the queue */
-                wait_for_completion(&complete);
-
-                if (!test_bit(BIO_UPTODATE, &bio->bi_flags)) {
+                if (submit_bio_wait(READ, bio)) {
                         printk(KERN_INFO
                                "btrfsic: read error at logical %llu dev %s!\n",
                                block_ctx->start, block_ctx->dev->name);
@@ -1740,11 +1731,6 @@ static int btrfsic_read_block(struct btrfsic_state *state,
         return block_ctx->len;
 }
 
-static void btrfsic_complete_bio_end_io(struct bio *bio, int err)
-{
-        complete((struct completion *)bio->bi_private);
-}
-
 static void btrfsic_dump_database(struct btrfsic_state *state)
 {
         struct list_head *elem_all;
@@ -3008,14 +2994,12 @@ int btrfsic_submit_bh(int rw, struct buffer_head *bh)
         return submit_bh(rw, bh);
 }
 
-void btrfsic_submit_bio(int rw, struct bio *bio)
+static void __btrfsic_submit_bio(int rw, struct bio *bio)
 {
         struct btrfsic_dev_state *dev_state;
 
-        if (!btrfsic_is_initialized) {
-                submit_bio(rw, bio);
+        if (!btrfsic_is_initialized)
                 return;
-        }
 
         mutex_lock(&btrfsic_mutex);
         /* since btrfsic_submit_bio() is also called before
@@ -3106,10 +3090,20 @@ void btrfsic_submit_bio(int rw, struct bio *bio)
         }
 leave:
         mutex_unlock(&btrfsic_mutex);
+}
 
+void btrfsic_submit_bio(int rw, struct bio *bio)
+{
+        __btrfsic_submit_bio(rw, bio);
         submit_bio(rw, bio);
 }
 
+int btrfsic_submit_bio_wait(int rw, struct bio *bio)
+{
+        __btrfsic_submit_bio(rw, bio);
+        return submit_bio_wait(rw, bio);
+}
+
 int btrfsic_mount(struct btrfs_root *root,
                   struct btrfs_fs_devices *fs_devices,
                   int including_extent_data, u32 print_mask)
diff --git a/fs/btrfs/check-integrity.h b/fs/btrfs/check-integrity.h
index 8b59175cc502..13b8566c97ab 100644
--- a/fs/btrfs/check-integrity.h
+++ b/fs/btrfs/check-integrity.h
@@ -22,9 +22,11 @@
 #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
 int btrfsic_submit_bh(int rw, struct buffer_head *bh);
 void btrfsic_submit_bio(int rw, struct bio *bio);
+int btrfsic_submit_bio_wait(int rw, struct bio *bio);
 #else
 #define btrfsic_submit_bh submit_bh
 #define btrfsic_submit_bio submit_bio
+#define btrfsic_submit_bio_wait submit_bio_wait
 #endif
 
 int btrfsic_mount(struct btrfs_root *root,
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 8e457fca0a0b..ff43802a7c88 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -1952,11 +1952,6 @@ static int free_io_failure(struct inode *inode, struct io_failure_record *rec,
         return err;
 }
 
-static void repair_io_failure_callback(struct bio *bio, int err)
-{
-        complete(bio->bi_private);
-}
-
 /*
  * this bypasses the standard btrfs submit functions deliberately, as
  * the standard behavior is to write all copies in a raid setup. here we only
@@ -1973,7 +1968,6 @@ int repair_io_failure(struct btrfs_fs_info *fs_info, u64 start,
 {
         struct bio *bio;
         struct btrfs_device *dev;
-        DECLARE_COMPLETION_ONSTACK(compl);
         u64 map_length = 0;
         u64 sector;
         struct btrfs_bio *bbio = NULL;
@@ -1990,8 +1984,6 @@ int repair_io_failure(struct btrfs_fs_info *fs_info, u64 start,
         bio = btrfs_io_bio_alloc(GFP_NOFS, 1);
         if (!bio)
                 return -EIO;
-        bio->bi_private = &compl;
-        bio->bi_end_io = repair_io_failure_callback;
         bio->bi_size = 0;
         map_length = length;
 
@@ -2012,10 +2004,8 @@ int repair_io_failure(struct btrfs_fs_info *fs_info, u64 start,
         }
         bio->bi_bdev = dev->bdev;
         bio_add_page(bio, page, length, start - page_offset(page));
-        btrfsic_submit_bio(WRITE_SYNC, bio);
-        wait_for_completion(&compl);
 
-        if (!test_bit(BIO_UPTODATE, &bio->bi_flags)) {
+        if (btrfsic_submit_bio_wait(WRITE_SYNC, bio)) {
                 /* try to remap that extent elsewhere? */
                 bio_put(bio);
                 btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_WRITE_ERRS);
diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index 561e2f16ba3e..1fd3f33c330a 100644
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -208,7 +208,6 @@ static void scrub_recheck_block_checksum(struct btrfs_fs_info *fs_info,
                                          int is_metadata, int have_csum,
                                          const u8 *csum, u64 generation,
                                          u16 csum_size);
-static void scrub_complete_bio_end_io(struct bio *bio, int err);
 static int scrub_repair_block_from_good_copy(struct scrub_block *sblock_bad,
                                              struct scrub_block *sblock_good,
                                              int force_write);
@@ -1294,7 +1293,6 @@ static void scrub_recheck_block(struct btrfs_fs_info *fs_info,
         for (page_num = 0; page_num < sblock->page_count; page_num++) {
                 struct bio *bio;
                 struct scrub_page *page = sblock->pagev[page_num];
-                DECLARE_COMPLETION_ONSTACK(complete);
 
                 if (page->dev->bdev == NULL) {
                         page->io_error = 1;
@@ -1311,18 +1309,11 @@ static void scrub_recheck_block(struct btrfs_fs_info *fs_info,
                 }
                 bio->bi_bdev = page->dev->bdev;
                 bio->bi_sector = page->physical >> 9;
-                bio->bi_end_io = scrub_complete_bio_end_io;
-                bio->bi_private = &complete;
 
                 bio_add_page(bio, page->page, PAGE_SIZE, 0);
-                btrfsic_submit_bio(READ, bio);
-
-                /* this will also unplug the queue */
-                wait_for_completion(&complete);
-
-                page->io_error = !test_bit(BIO_UPTODATE, &bio->bi_flags);
-                if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
+                if (btrfsic_submit_bio_wait(READ, bio))
                         sblock->no_io_error_seen = 0;
+
                 bio_put(bio);
         }
 
@@ -1391,11 +1382,6 @@ static void scrub_recheck_block_checksum(struct btrfs_fs_info *fs_info,
                 sblock->checksum_error = 1;
 }
 
-static void scrub_complete_bio_end_io(struct bio *bio, int err)
-{
-        complete((struct completion *)bio->bi_private);
-}
-
 static int scrub_repair_block_from_good_copy(struct scrub_block *sblock_bad,
                                              struct scrub_block *sblock_good,
                                              int force_write)
@@ -1430,7 +1416,6 @@ static int scrub_repair_page_from_good_copy(struct scrub_block *sblock_bad,
             sblock_bad->checksum_error || page_bad->io_error) {
                 struct bio *bio;
                 int ret;
-                DECLARE_COMPLETION_ONSTACK(complete);
 
                 if (!page_bad->dev->bdev) {
                         printk_ratelimited(KERN_WARNING
@@ -1443,19 +1428,14 @@ static int scrub_repair_page_from_good_copy(struct scrub_block *sblock_bad,
                         return -EIO;
                 bio->bi_bdev = page_bad->dev->bdev;
                 bio->bi_sector = page_bad->physical >> 9;
-                bio->bi_end_io = scrub_complete_bio_end_io;
-                bio->bi_private = &complete;
 
                 ret = bio_add_page(bio, page_good->page, PAGE_SIZE, 0);
                 if (PAGE_SIZE != ret) {
                         bio_put(bio);
                         return -EIO;
                 }
-                btrfsic_submit_bio(WRITE, bio);
 
-                /* this will also unplug the queue */
-                wait_for_completion(&complete);
-                if (!bio_flagged(bio, BIO_UPTODATE)) {
+                if (btrfsic_submit_bio_wait(WRITE, bio)) {
                         btrfs_dev_stat_inc_and_print(page_bad->dev,
                                 BTRFS_DEV_STAT_WRITE_ERRS);
                         btrfs_dev_replace_stats_inc(
@@ -3375,7 +3355,6 @@ static int write_page_nocow(struct scrub_ctx *sctx,
         struct bio *bio;
         struct btrfs_device *dev;
         int ret;
-        DECLARE_COMPLETION_ONSTACK(compl);
 
         dev = sctx->wr_ctx.tgtdev;
         if (!dev)
@@ -3392,8 +3371,6 @@ static int write_page_nocow(struct scrub_ctx *sctx,
                 spin_unlock(&sctx->stat_lock);
                 return -ENOMEM;
         }
-        bio->bi_private = &compl;
-        bio->bi_end_io = scrub_complete_bio_end_io;
         bio->bi_size = 0;
         bio->bi_sector = physical_for_dev_replace >> 9;
         bio->bi_bdev = dev->bdev;
@@ -3404,10 +3381,8 @@ leave_with_eio:
                 btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_WRITE_ERRS);
                 return -EIO;
         }
-        btrfsic_submit_bio(WRITE_SYNC, bio);
-        wait_for_completion(&compl);
 
-        if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
+        if (btrfsic_submit_bio_wait(WRITE_SYNC, bio))
                 goto leave_with_eio;
 
         bio_put(bio);
diff --git a/fs/hfsplus/wrapper.c b/fs/hfsplus/wrapper.c
index b51a6079108d..e9a97a0d4314 100644
--- a/fs/hfsplus/wrapper.c
+++ b/fs/hfsplus/wrapper.c
@@ -24,13 +24,6 @@ struct hfsplus_wd {
         u16 embed_count;
 };
 
-static void hfsplus_end_io_sync(struct bio *bio, int err)
-{
-        if (err)
-                clear_bit(BIO_UPTODATE, &bio->bi_flags);
-        complete(bio->bi_private);
-}
-
 /*
  * hfsplus_submit_bio - Perfrom block I/O
  * @sb: super block of volume for I/O
@@ -53,7 +46,6 @@ static void hfsplus_end_io_sync(struct bio *bio, int err)
 int hfsplus_submit_bio(struct super_block *sb, sector_t sector,
                 void *buf, void **data, int rw)
 {
-        DECLARE_COMPLETION_ONSTACK(wait);
         struct bio *bio;
         int ret = 0;
         u64 io_size;
@@ -73,8 +65,6 @@ int hfsplus_submit_bio(struct super_block *sb, sector_t sector,
         bio = bio_alloc(GFP_NOIO, 1);
         bio->bi_sector = sector;
         bio->bi_bdev = sb->s_bdev;
-        bio->bi_end_io = hfsplus_end_io_sync;
-        bio->bi_private = &wait;
 
         if (!(rw & WRITE) && data)
                 *data = (u8 *)buf + offset;
@@ -93,12 +83,7 @@ int hfsplus_submit_bio(struct super_block *sb, sector_t sector,
                 buf = (u8 *)buf + len;
         }
 
-        submit_bio(rw, bio);
-        wait_for_completion(&wait);
-
-        if (!bio_flagged(bio, BIO_UPTODATE))
-                ret = -EIO;
-
+        ret = submit_bio_wait(rw, bio);
 out:
         bio_put(bio);
         return ret < 0 ? ret : 0;
diff --git a/fs/logfs/dev_bdev.c b/fs/logfs/dev_bdev.c
index 550475ca6a0e..0f95f0d0b313 100644
--- a/fs/logfs/dev_bdev.c
+++ b/fs/logfs/dev_bdev.c
@@ -14,16 +14,10 @@
 
 #define PAGE_OFS(ofs) ((ofs) & (PAGE_SIZE-1))
 
-static void request_complete(struct bio *bio, int err)
-{
-        complete((struct completion *)bio->bi_private);
-}
-
 static int sync_request(struct page *page, struct block_device *bdev, int rw)
 {
         struct bio bio;
         struct bio_vec bio_vec;
-        struct completion complete;
 
         bio_init(&bio);
         bio.bi_max_vecs = 1;
@@ -35,13 +29,8 @@ static int sync_request(struct page *page, struct block_device *bdev, int rw)
         bio.bi_size = PAGE_SIZE;
         bio.bi_bdev = bdev;
         bio.bi_sector = page->index * (PAGE_SIZE >> 9);
-        init_completion(&complete);
-        bio.bi_private = &complete;
-        bio.bi_end_io = request_complete;
 
-        submit_bio(rw, &bio);
-        wait_for_completion(&complete);
-        return test_bit(BIO_UPTODATE, &bio.bi_flags) ? 0 : -EIO;
+        return submit_bio_wait(rw, &bio);
 }
 
 static int bdev_readpage(void *_sb, struct page *page)