Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net

Fun set of conflict resolutions here...

For the mac80211 stuff, these were fortunately just parallel
adds.  Trivially resolved.

In drivers/net/phy/phy.c we had a bug fix in 'net' that moved the
function phy_disable_interrupts() earlier in the file, whilst in
'net-next' the phy_error() call from this function was removed.

In net/ipv4/xfrm4_policy.c, David Ahern's changes to remove the
'rt_table_id' member of rtable collided with a bug fix in 'net' that
added a new struct member "rt_mtu_locked" which needs to be copied
over here.

The mlxsw driver conflict consisted of net-next separating
the span code and definitions into separate files, whilst
a 'net' bug fix made some changes to that moved code.

The mlx5 infiniband conflict resolution was quite non-trivial,
the RDMA tree's merge commit was used as a guide here, and
here are their notes:

====================

    Due to bug fixes found by the syzkaller bot and taken into the for-rc
    branch after development for the 4.17 merge window had already started
    being taken into the for-next branch, there were fairly non-trivial
    merge issues that would need to be resolved between the for-rc branch
    and the for-next branch.  This merge resolves those conflicts and
    provides a unified base upon which ongoing development for 4.17 can
    be based.

    Conflicts:
            drivers/infiniband/hw/mlx5/main.c - Commit 42cea83f9524
            (IB/mlx5: Fix cleanup order on unload) added to for-rc and
            commit b5ca15ad7e61 (IB/mlx5: Add proper representors support)
            add as part of the devel cycle both needed to modify the
            init/de-init functions used by mlx5.  To support the new
            representors, the new functions added by the cleanup patch
            needed to be made non-static, and the init/de-init list
            added by the representors patch needed to be modified to
            match the init/de-init list changes made by the cleanup
            patch.
    Updates:
            drivers/infiniband/hw/mlx5/mlx5_ib.h - Update function
            prototypes added by representors patch to reflect new function
            names as changed by cleanup patch
            drivers/infiniband/hw/mlx5/ib_rep.c - Update init/de-init
            stage list to match new order from cleanup patch
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

22 files changed, 436 insertions, 185 deletions

diff --git a/fs/aio.c b/fs/aio.c
index a062d75109cb..6bcd3fb5265a 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -68,9 +68,9 @@ struct aio_ring {
 #define AIO_RING_PAGES  8
 
 struct kioctx_table {
-        struct rcu_head rcu;
-        unsigned        nr;
-        struct kioctx   *table[];
+        struct rcu_head         rcu;
+        unsigned                nr;
+        struct kioctx __rcu     *table[];
 };
 
 struct kioctx_cpu {
@@ -115,7 +115,8 @@ struct kioctx {
         struct page             **ring_pages;
         long                    nr_pages;
 
-        struct work_struct      free_work;
+        struct rcu_head         free_rcu;
+        struct work_struct      free_work;      /* see free_ioctx() */
 
         /*
          * signals when all in-flight requests are done
@@ -329,7 +330,7 @@ static int aio_ring_mremap(struct vm_area_struct *vma)
         for (i = 0; i < table->nr; i++) {
                 struct kioctx *ctx;
 
-                ctx = table->table[i];
+                ctx = rcu_dereference(table->table[i]);
                 if (ctx && ctx->aio_ring_file == file) {
                         if (!atomic_read(&ctx->dead)) {
                                 ctx->user_id = ctx->mmap_base = vma->vm_start;
@@ -588,6 +589,12 @@ static int kiocb_cancel(struct aio_kiocb *kiocb)
         return cancel(&kiocb->common);
 }
 
+/*
+ * free_ioctx() should be RCU delayed to synchronize against the RCU
+ * protected lookup_ioctx() and also needs process context to call
+ * aio_free_ring(), so the double bouncing through kioctx->free_rcu and
+ * ->free_work.
+ */
 static void free_ioctx(struct work_struct *work)
 {
         struct kioctx *ctx = container_of(work, struct kioctx, free_work);
@@ -601,6 +608,14 @@ static void free_ioctx(struct work_struct *work)
         kmem_cache_free(kioctx_cachep, ctx);
 }
 
+static void free_ioctx_rcufn(struct rcu_head *head)
+{
+        struct kioctx *ctx = container_of(head, struct kioctx, free_rcu);
+
+        INIT_WORK(&ctx->free_work, free_ioctx);
+        schedule_work(&ctx->free_work);
+}
+
 static void free_ioctx_reqs(struct percpu_ref *ref)
 {
         struct kioctx *ctx = container_of(ref, struct kioctx, reqs);
@@ -609,8 +624,8 @@ static void free_ioctx_reqs(struct percpu_ref *ref)
         if (ctx->rq_wait && atomic_dec_and_test(&ctx->rq_wait->count))
                 complete(&ctx->rq_wait->comp);
 
-        INIT_WORK(&ctx->free_work, free_ioctx);
-        schedule_work(&ctx->free_work);
+        /* Synchronize against RCU protected table->table[] dereferences */
+        call_rcu(&ctx->free_rcu, free_ioctx_rcufn);
 }
 
 /*
@@ -651,9 +666,9 @@ static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm)
         while (1) {
                 if (table)
                         for (i = 0; i < table->nr; i++)
-                                if (!table->table[i]) {
+                                if (!rcu_access_pointer(table->table[i])) {
                                         ctx->id = i;
-                                        table->table[i] = ctx;
+                                        rcu_assign_pointer(table->table[i], ctx);
                                         spin_unlock(&mm->ioctx_lock);
 
                                         /* While kioctx setup is in progress,
@@ -834,11 +849,11 @@ static int kill_ioctx(struct mm_struct *mm, struct kioctx *ctx,
         }
 
         table = rcu_dereference_raw(mm->ioctx_table);
-        WARN_ON(ctx != table->table[ctx->id]);
-        table->table[ctx->id] = NULL;
+        WARN_ON(ctx != rcu_access_pointer(table->table[ctx->id]));
+        RCU_INIT_POINTER(table->table[ctx->id], NULL);
         spin_unlock(&mm->ioctx_lock);
 
-        /* percpu_ref_kill() will do the necessary call_rcu() */
+        /* free_ioctx_reqs() will do the necessary RCU synchronization */
         wake_up_all(&ctx->wait);
 
         /*
@@ -880,7 +895,8 @@ void exit_aio(struct mm_struct *mm)
 
         skipped = 0;
         for (i = 0; i < table->nr; ++i) {
-                struct kioctx *ctx = table->table[i];
+                struct kioctx *ctx =
+                        rcu_dereference_protected(table->table[i], true);
 
                 if (!ctx) {
                         skipped++;
@@ -1069,7 +1085,7 @@ static struct kioctx *lookup_ioctx(unsigned long ctx_id)
         if (!table || id >= table->nr)
                 goto out;
 
-        ctx = table->table[id];
+        ctx = rcu_dereference(table->table[id]);
         if (ctx && ctx->user_id == ctx_id) {
                 percpu_ref_get(&ctx->users);
                 ret = ctx;
diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
index f94b2d8c744a..26484648d090 100644
--- a/fs/btrfs/backref.c
+++ b/fs/btrfs/backref.c
@@ -1519,6 +1519,7 @@ int btrfs_check_shared(struct btrfs_root *root, u64 inum, u64 bytenr)
                 if (!node)
                         break;
                 bytenr = node->val;
+                shared.share_count = 0;
                 cond_resched();
         }
 
diff --git a/fs/btrfs/raid56.c b/fs/btrfs/raid56.c
index dec0907dfb8a..fcfc20de2df3 100644
--- a/fs/btrfs/raid56.c
+++ b/fs/btrfs/raid56.c
@@ -1370,6 +1370,7 @@ static int find_bio_stripe(struct btrfs_raid_bio *rbio,
                 stripe_start = stripe->physical;
                 if (physical >= stripe_start &&
                     physical < stripe_start + rbio->stripe_len &&
+                    stripe->dev->bdev &&
                     bio->bi_disk == stripe->dev->bdev->bd_disk &&
                     bio->bi_partno == stripe->dev->bdev->bd_partno) {
                         return i;
diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index d11c70bff5a9..a8bafed931f4 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -423,7 +423,7 @@ static ssize_t btrfs_nodesize_show(struct kobject *kobj,
 {
         struct btrfs_fs_info *fs_info = to_fs_info(kobj);
 
-        return snprintf(buf, PAGE_SIZE, "%u\n", fs_info->nodesize);
+        return snprintf(buf, PAGE_SIZE, "%u\n", fs_info->super_copy->nodesize);
 }
 
 BTRFS_ATTR(, nodesize, btrfs_nodesize_show);
@@ -433,7 +433,8 @@ static ssize_t btrfs_sectorsize_show(struct kobject *kobj,
 {
         struct btrfs_fs_info *fs_info = to_fs_info(kobj);
 
-        return snprintf(buf, PAGE_SIZE, "%u\n", fs_info->sectorsize);
+        return snprintf(buf, PAGE_SIZE, "%u\n",
+                        fs_info->super_copy->sectorsize);
 }
 
 BTRFS_ATTR(, sectorsize, btrfs_sectorsize_show);
@@ -443,7 +444,8 @@ static ssize_t btrfs_clone_alignment_show(struct kobject *kobj,
 {
         struct btrfs_fs_info *fs_info = to_fs_info(kobj);
 
-        return snprintf(buf, PAGE_SIZE, "%u\n", fs_info->sectorsize);
+        return snprintf(buf, PAGE_SIZE, "%u\n",
+                        fs_info->super_copy->sectorsize);
 }
 
 BTRFS_ATTR(, clone_alignment, btrfs_clone_alignment_show);
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 9220f004001c..04f07144b45c 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -1722,23 +1722,19 @@ static void update_super_roots(struct btrfs_fs_info *fs_info)
 
         super = fs_info->super_copy;
 
-        /* update latest btrfs_super_block::chunk_root refs */
         root_item = &fs_info->chunk_root->root_item;
-        btrfs_set_super_chunk_root(super, root_item->bytenr);
-        btrfs_set_super_chunk_root_generation(super, root_item->generation);
-        btrfs_set_super_chunk_root_level(super, root_item->level);
+        super->chunk_root = root_item->bytenr;
+        super->chunk_root_generation = root_item->generation;
+        super->chunk_root_level = root_item->level;
 
-        /* update latest btrfs_super_block::root refs */
         root_item = &fs_info->tree_root->root_item;
-        btrfs_set_super_root(super, root_item->bytenr);
-        btrfs_set_super_generation(super, root_item->generation);
-        btrfs_set_super_root_level(super, root_item->level);
-
+        super->root = root_item->bytenr;
+        super->generation = root_item->generation;
+        super->root_level = root_item->level;
         if (btrfs_test_opt(fs_info, SPACE_CACHE))
-                btrfs_set_super_cache_generation(super, root_item->generation);
+                super->cache_generation = root_item->generation;
         if (test_bit(BTRFS_FS_UPDATE_UUID_TREE_GEN, &fs_info->flags))
-                btrfs_set_super_uuid_tree_generation(super,
-                                                     root_item->generation);
+                super->uuid_tree_generation = root_item->generation;
 }
 
 int btrfs_transaction_in_commit(struct btrfs_fs_info *info)
diff --git a/fs/dcache.c b/fs/dcache.c
index 7c38f39958bc..8945e6cabd93 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -647,11 +647,16 @@ again:
                 spin_unlock(&parent->d_lock);
                 goto again;
         }
-        rcu_read_unlock();
-        if (parent != dentry)
+        if (parent != dentry) {
                 spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
-        else
+                if (unlikely(dentry->d_lockref.count < 0)) {
+                        spin_unlock(&parent->d_lock);
+                        parent = NULL;
+                }
+        } else {
                 parent = NULL;
+        }
+        rcu_read_unlock();
         return parent;
 }
 
@@ -2474,7 +2479,7 @@ struct dentry *d_alloc_parallel(struct dentry *parent,
 
 retry:
         rcu_read_lock();
-        seq = smp_load_acquire(&parent->d_inode->i_dir_seq) & ~1;
+        seq = smp_load_acquire(&parent->d_inode->i_dir_seq);
         r_seq = read_seqbegin(&rename_lock);
         dentry = __d_lookup_rcu(parent, name, &d_seq);
         if (unlikely(dentry)) {
@@ -2495,8 +2500,14 @@ retry:
                 rcu_read_unlock();
                 goto retry;
         }
+
+        if (unlikely(seq & 1)) {
+                rcu_read_unlock();
+                goto retry;
+        }
+
         hlist_bl_lock(b);
-        if (unlikely(parent->d_inode->i_dir_seq != seq)) {
+        if (unlikely(READ_ONCE(parent->d_inode->i_dir_seq) != seq)) {
                 hlist_bl_unlock(b);
                 rcu_read_unlock();
                 goto retry;
diff --git a/fs/gfs2/bmap.c b/fs/gfs2/bmap.c
index 86d6a4435c87..51f940e76c5e 100644
--- a/fs/gfs2/bmap.c
+++ b/fs/gfs2/bmap.c
@@ -807,9 +807,6 @@ do_alloc:
                         iomap->length = hole_size(inode, lblock, &mp);
                 else
                         iomap->length = size - pos;
-        } else {
-                if (height <= ip->i_height)
-                        iomap->length = hole_size(inode, lblock, &mp);
         }
         goto out_release;
 }
diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index 8fe1b0aa2896..b9a254dcc0e7 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -108,6 +108,16 @@ static void huge_pagevec_release(struct pagevec *pvec)
         pagevec_reinit(pvec);
 }
 
+/*
+ * Mask used when checking the page offset value passed in via system
+ * calls.  This value will be converted to a loff_t which is signed.
+ * Therefore, we want to check the upper PAGE_SHIFT + 1 bits of the
+ * value.  The extra bit (- 1 in the shift value) is to take the sign
+ * bit into account.
+ */
+#define PGOFF_LOFFT_MAX \
+        (((1UL << (PAGE_SHIFT + 1)) - 1) <<  (BITS_PER_LONG - (PAGE_SHIFT + 1)))
+
 static int hugetlbfs_file_mmap(struct file *file, struct vm_area_struct *vma)
 {
         struct inode *inode = file_inode(file);
@@ -127,12 +137,13 @@ static int hugetlbfs_file_mmap(struct file *file, struct vm_area_struct *vma)
         vma->vm_ops = &hugetlb_vm_ops;
 
         /*
-         * Offset passed to mmap (before page shift) could have been
-         * negative when represented as a (l)off_t.
+         * page based offset in vm_pgoff could be sufficiently large to
+         * overflow a (l)off_t when converted to byte offset.
          */
-        if (((loff_t)vma->vm_pgoff << PAGE_SHIFT) < 0)
+        if (vma->vm_pgoff & PGOFF_LOFFT_MAX)
                 return -EINVAL;
 
+        /* must be huge page aligned */
         if (vma->vm_pgoff & (~huge_page_mask(h) >> PAGE_SHIFT))
                 return -EINVAL;
 
diff --git a/fs/namei.c b/fs/namei.c
index 921ae32dbc80..cafa365eeb70 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -559,9 +559,10 @@ static int __nd_alloc_stack(struct nameidata *nd)
 static bool path_connected(const struct path *path)
 {
         struct vfsmount *mnt = path->mnt;
+        struct super_block *sb = mnt->mnt_sb;
 
-        /* Only bind mounts can have disconnected paths */
-        if (mnt->mnt_root == mnt->mnt_sb->s_root)
+        /* Bind mounts and multi-root filesystems can have disconnected paths */
+        if (!(sb->s_iflags & SB_I_MULTIROOT) && (mnt->mnt_root == sb->s_root))
                 return true;
 
         return is_subdir(path->dentry, mnt->mnt_root);
diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
index 8c10b0562e75..621c517b325c 100644
--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -86,10 +86,10 @@ struct nfs_direct_req {
         struct nfs_direct_mirror mirrors[NFS_PAGEIO_DESCRIPTOR_MIRROR_MAX];
         int                     mirror_count;
 
+        loff_t                  io_start;       /* Start offset for I/O */
         ssize_t                 count,          /* bytes actually processed */
                                 max_count,      /* max expected count */
                                 bytes_left,     /* bytes left to be sent */
-                                io_start,       /* start of IO */
                                 error;          /* any reported error */
         struct completion       completion;     /* wait for i/o completion */
 
diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index c13e826614b5..ee723aa153a3 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -292,8 +292,11 @@ pnfs_detach_layout_hdr(struct pnfs_layout_hdr *lo)
 void
 pnfs_put_layout_hdr(struct pnfs_layout_hdr *lo)
 {
-        struct inode *inode = lo->plh_inode;
+        struct inode *inode;
 
+        if (!lo)
+                return;
+        inode = lo->plh_inode;
         pnfs_layoutreturn_before_put_layout_hdr(lo);
 
         if (refcount_dec_and_lock(&lo->plh_refcount, &inode->i_lock)) {
@@ -1241,10 +1244,12 @@ retry:
         spin_lock(&ino->i_lock);
         lo = nfsi->layout;
         if (!lo || !pnfs_layout_is_valid(lo) ||
-            test_bit(NFS_LAYOUT_BULK_RECALL, &lo->plh_flags))
+            test_bit(NFS_LAYOUT_BULK_RECALL, &lo->plh_flags)) {
+                lo = NULL;
                 goto out_noroc;
+        }
+        pnfs_get_layout_hdr(lo);
         if (test_bit(NFS_LAYOUT_RETURN_LOCK, &lo->plh_flags)) {
-                pnfs_get_layout_hdr(lo);
                 spin_unlock(&ino->i_lock);
                 wait_on_bit(&lo->plh_flags, NFS_LAYOUT_RETURN,
                                 TASK_UNINTERRUPTIBLE);
@@ -1312,10 +1317,12 @@ out_noroc:
                 struct pnfs_layoutdriver_type *ld = NFS_SERVER(ino)->pnfs_curr_ld;
                 if (ld->prepare_layoutreturn)
                         ld->prepare_layoutreturn(args);
+                pnfs_put_layout_hdr(lo);
                 return true;
         }
         if (layoutreturn)
                 pnfs_send_layoutreturn(lo, &stateid, iomode, true);
+        pnfs_put_layout_hdr(lo);
         return false;
 }
 
diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index 29bacdc56f6a..5e470e233c83 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -2631,6 +2631,8 @@ struct dentry *nfs_fs_mount_common(struct nfs_server *server,
                 /* initial superblock/root creation */
                 mount_info->fill_super(s, mount_info);
                 nfs_get_cache_cookie(s, mount_info->parsed, mount_info->cloned);
+                if (!(server->flags & NFS_MOUNT_UNSHARED))
+                        s->s_iflags |= SB_I_MULTIROOT;
         }
 
         mntroot = nfs_get_root(s, mount_info->mntfh, dev_name);
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 7428a669d7a7..e7d8ceae8f26 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -1876,40 +1876,43 @@ int nfs_generic_commit_list(struct inode *inode, struct list_head *head,
         return status;
 }
 
-int nfs_commit_inode(struct inode *inode, int how)
+static int __nfs_commit_inode(struct inode *inode, int how,
+                struct writeback_control *wbc)
 {
         LIST_HEAD(head);
         struct nfs_commit_info cinfo;
         int may_wait = how & FLUSH_SYNC;
-        int error = 0;
-        int res;
+        int ret, nscan;
 
         nfs_init_cinfo_from_inode(&cinfo, inode);
         nfs_commit_begin(cinfo.mds);
-        res = nfs_scan_commit(inode, &head, &cinfo);
-        if (res)
-                error = nfs_generic_commit_list(inode, &head, how, &cinfo);
+        for (;;) {
+                ret = nscan = nfs_scan_commit(inode, &head, &cinfo);
+                if (ret <= 0)
+                        break;
+                ret = nfs_generic_commit_list(inode, &head, how, &cinfo);
+                if (ret < 0)
+                        break;
+                ret = 0;
+                if (wbc && wbc->sync_mode == WB_SYNC_NONE) {
+                        if (nscan < wbc->nr_to_write)
+                                wbc->nr_to_write -= nscan;
+                        else
+                                wbc->nr_to_write = 0;
+                }
+                if (nscan < INT_MAX)
+                        break;
+                cond_resched();
+        }
         nfs_commit_end(cinfo.mds);
-        if (res == 0)
-                return res;
-        if (error < 0)
-                goto out_error;
-        if (!may_wait)
-                goto out_mark_dirty;
-        error = wait_on_commit(cinfo.mds);
-        if (error < 0)
-                return error;
-        return res;
-out_error:
-        res = error;
-        /* Note: If we exit without ensuring that the commit is complete,
-         * we must mark the inode as dirty. Otherwise, future calls to
-         * sync_inode() with the WB_SYNC_ALL flag set will fail to ensure
-         * that the data is on the disk.
-         */
-out_mark_dirty:
-        __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
-        return res;
+        if (ret || !may_wait)
+                return ret;
+        return wait_on_commit(cinfo.mds);
+}
+
+int nfs_commit_inode(struct inode *inode, int how)
+{
+        return __nfs_commit_inode(inode, how, NULL);
 }
 EXPORT_SYMBOL_GPL(nfs_commit_inode);
 
@@ -1919,11 +1922,11 @@ int nfs_write_inode(struct inode *inode, struct writeback_control *wbc)
         int flags = FLUSH_SYNC;
         int ret = 0;
 
-        /* no commits means nothing needs to be done */
-        if (!atomic_long_read(&nfsi->commit_info.ncommit))
-                return ret;
-
         if (wbc->sync_mode == WB_SYNC_NONE) {
+                /* no commits means nothing needs to be done */
+                if (!atomic_long_read(&nfsi->commit_info.ncommit))
+                        goto check_requests_outstanding;
+
                 /* Don't commit yet if this is a non-blocking flush and there
                  * are a lot of outstanding writes for this mapping.
                  */
@@ -1934,16 +1937,16 @@ int nfs_write_inode(struct inode *inode, struct writeback_control *wbc)
                 flags = 0;
         }
 
-        ret = nfs_commit_inode(inode, flags);
-        if (ret >= 0) {
-                if (wbc->sync_mode == WB_SYNC_NONE) {
-                        if (ret < wbc->nr_to_write)
-                                wbc->nr_to_write -= ret;
-                        else
-                                wbc->nr_to_write = 0;
-                }
-                return 0;
-        }
+        ret = __nfs_commit_inode(inode, flags, wbc);
+        if (!ret) {
+                if (flags & FLUSH_SYNC)
+                        return 0;
+        } else if (atomic_long_read(&nfsi->commit_info.ncommit))
+                goto out_mark_dirty;
+
+check_requests_outstanding:
+        if (!atomic_read(&nfsi->commit_info.rpcs_out))
+                return ret;
 out_mark_dirty:
         __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
         return ret;
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 150521c9671b..61b770e39809 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -268,6 +268,35 @@ free_blocked_lock(struct nfsd4_blocked_lock *nbl)
         kfree(nbl);
 }
 
+static void
+remove_blocked_locks(struct nfs4_lockowner *lo)
+{
+        struct nfs4_client *clp = lo->lo_owner.so_client;
+        struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);
+        struct nfsd4_blocked_lock *nbl;
+        LIST_HEAD(reaplist);
+
+        /* Dequeue all blocked locks */
+        spin_lock(&nn->blocked_locks_lock);
+        while (!list_empty(&lo->lo_blocked)) {
+                nbl = list_first_entry(&lo->lo_blocked,
+                                        struct nfsd4_blocked_lock,
+                                        nbl_list);
+                list_del_init(&nbl->nbl_list);
+                list_move(&nbl->nbl_lru, &reaplist);
+        }
+        spin_unlock(&nn->blocked_locks_lock);
+
+        /* Now free them */
+        while (!list_empty(&reaplist)) {
+                nbl = list_first_entry(&reaplist, struct nfsd4_blocked_lock,
+                                        nbl_lru);
+                list_del_init(&nbl->nbl_lru);
+                posix_unblock_lock(&nbl->nbl_lock);
+                free_blocked_lock(nbl);
+        }
+}
+
 static int
 nfsd4_cb_notify_lock_done(struct nfsd4_callback *cb, struct rpc_task *task)
 {
@@ -1866,6 +1895,7 @@ static __be32 mark_client_expired_locked(struct nfs4_client *clp)
 static void
 __destroy_client(struct nfs4_client *clp)
 {
+        int i;
         struct nfs4_openowner *oo;
         struct nfs4_delegation *dp;
         struct list_head reaplist;
@@ -1895,6 +1925,16 @@ __destroy_client(struct nfs4_client *clp)
                 nfs4_get_stateowner(&oo->oo_owner);
                 release_openowner(oo);
         }
+        for (i = 0; i < OWNER_HASH_SIZE; i++) {
+                struct nfs4_stateowner *so, *tmp;
+
+                list_for_each_entry_safe(so, tmp, &clp->cl_ownerstr_hashtbl[i],
+                                         so_strhash) {
+                        /* Should be no openowners at this point */
+                        WARN_ON_ONCE(so->so_is_open_owner);
+                        remove_blocked_locks(lockowner(so));
+                }
+        }
         nfsd4_return_all_client_layouts(clp);
         nfsd4_shutdown_callback(clp);
         if (clp->cl_cb_conn.cb_xprt)
@@ -6355,6 +6395,7 @@ nfsd4_release_lockowner(struct svc_rqst *rqstp,
         }
         spin_unlock(&clp->cl_lock);
         free_ol_stateid_reaplist(&reaplist);
+        remove_blocked_locks(lo);
         nfs4_put_stateowner(&lo->lo_owner);
 
         return status;
@@ -7140,6 +7181,8 @@ nfs4_state_destroy_net(struct net *net)
                 }
         }
 
+        WARN_ON(!list_empty(&nn->blocked_locks_lru));
+
         for (i = 0; i < CLIENT_HASH_SIZE; i++) {
                 while (!list_empty(&nn->unconf_id_hashtbl[i])) {
                         clp = list_entry(nn->unconf_id_hashtbl[i].next, struct nfs4_client, cl_idhash);
@@ -7206,7 +7249,6 @@ nfs4_state_shutdown_net(struct net *net)
         struct nfs4_delegation *dp = NULL;
         struct list_head *pos, *next, reaplist;
         struct nfsd_net *nn = net_generic(net, nfsd_net_id);
-        struct nfsd4_blocked_lock *nbl;
 
         cancel_delayed_work_sync(&nn->laundromat_work);
         locks_end_grace(&nn->nfsd4_manager);
@@ -7227,24 +7269,6 @@ nfs4_state_shutdown_net(struct net *net)
                 nfs4_put_stid(&dp->dl_stid);
         }
 
-        BUG_ON(!list_empty(&reaplist));
-        spin_lock(&nn->blocked_locks_lock);
-        while (!list_empty(&nn->blocked_locks_lru)) {
-                nbl = list_first_entry(&nn->blocked_locks_lru,
-                                        struct nfsd4_blocked_lock, nbl_lru);
-                list_move(&nbl->nbl_lru, &reaplist);
-                list_del_init(&nbl->nbl_list);
-        }
-        spin_unlock(&nn->blocked_locks_lock);
-
-        while (!list_empty(&reaplist)) {
-                nbl = list_first_entry(&reaplist,
-                                        struct nfsd4_blocked_lock, nbl_lru);
-                list_del_init(&nbl->nbl_lru);
-                posix_unblock_lock(&nbl->nbl_lock);
-                free_blocked_lock(nbl);
-        }
-
         nfsd4_client_tracking_exit(net);
         nfs4_state_destroy_net(net);
 }
diff --git a/fs/overlayfs/Kconfig b/fs/overlayfs/Kconfig
index 406e72de88f6..ce6ff5a0a6e4 100644
--- a/fs/overlayfs/Kconfig
+++ b/fs/overlayfs/Kconfig
@@ -24,6 +24,8 @@ config OVERLAY_FS_REDIRECT_DIR
           an overlay which has redirects on a kernel that doesn't support this
           feature will have unexpected results.
 
+          If unsure, say N.
+
 config OVERLAY_FS_REDIRECT_ALWAYS_FOLLOW
         bool "Overlayfs: follow redirects even if redirects are turned off"
         default y
@@ -32,8 +34,13 @@ config OVERLAY_FS_REDIRECT_ALWAYS_FOLLOW
           Disable this to get a possibly more secure configuration, but that
           might not be backward compatible with previous kernels.
 
+          If backward compatibility is not an issue, then it is safe and
+          recommended to say N here.
+
           For more information, see Documentation/filesystems/overlayfs.txt
 
+          If unsure, say Y.
+
 config OVERLAY_FS_INDEX
         bool "Overlayfs: turn on inodes index feature by default"
         depends on OVERLAY_FS
@@ -51,6 +58,8 @@ config OVERLAY_FS_INDEX
           That is, mounting an overlay which has an inodes index on a kernel
           that doesn't support this feature will have unexpected results.
 
+          If unsure, say N.
+
 config OVERLAY_FS_NFS_EXPORT
         bool "Overlayfs: turn on NFS export feature by default"
         depends on OVERLAY_FS
@@ -72,3 +81,8 @@ config OVERLAY_FS_NFS_EXPORT
           Note, that the NFS export feature is not backward compatible.
           That is, mounting an overlay which has a full index on a kernel
           that doesn't support this feature will have unexpected results.
+
+          Most users should say N here and enable this feature on a case-by-
+          case basis with the "nfs_export=on" mount option.
+
+          Say N unless you fully understand the consequences.
diff --git a/fs/overlayfs/export.c b/fs/overlayfs/export.c
index bb94ce9da5c8..87bd4148f4fb 100644
--- a/fs/overlayfs/export.c
+++ b/fs/overlayfs/export.c
@@ -19,6 +19,142 @@
 #include <linux/ratelimit.h>
 #include "overlayfs.h"
 
+static int ovl_encode_maybe_copy_up(struct dentry *dentry)
+{
+        int err;
+
+        if (ovl_dentry_upper(dentry))
+                return 0;
+
+        err = ovl_want_write(dentry);
+        if (!err) {
+                err = ovl_copy_up(dentry);
+                ovl_drop_write(dentry);
+        }
+
+        if (err) {
+                pr_warn_ratelimited("overlayfs: failed to copy up on encode (%pd2, err=%i)\n",
+                                    dentry, err);
+        }
+
+        return err;
+}
+
+/*
+ * Before encoding a non-upper directory file handle from real layer N, we need
+ * to check if it will be possible to reconnect an overlay dentry from the real
+ * lower decoded dentry. This is done by following the overlay ancestry up to a
+ * "layer N connected" ancestor and verifying that all parents along the way are
+ * "layer N connectable". If an ancestor that is NOT "layer N connectable" is
+ * found, we need to copy up an ancestor, which is "layer N connectable", thus
+ * making that ancestor "layer N connected". For example:
+ *
+ * layer 1: /a
+ * layer 2: /a/b/c
+ *
+ * The overlay dentry /a is NOT "layer 2 connectable", because if dir /a is
+ * copied up and renamed, upper dir /a will be indexed by lower dir /a from
+ * layer 1. The dir /a from layer 2 will never be indexed, so the algorithm (*)
+ * in ovl_lookup_real_ancestor() will not be able to lookup a connected overlay
+ * dentry from the connected lower dentry /a/b/c.
+ *
+ * To avoid this problem on decode time, we need to copy up an ancestor of
+ * /a/b/c, which is "layer 2 connectable", on encode time. That ancestor is
+ * /a/b. After copy up (and index) of /a/b, it will become "layer 2 connected"
+ * and when the time comes to decode the file handle from lower dentry /a/b/c,
+ * ovl_lookup_real_ancestor() will find the indexed ancestor /a/b and decoding
+ * a connected overlay dentry will be accomplished.
+ *
+ * (*) the algorithm in ovl_lookup_real_ancestor() can be improved to lookup an
+ * entry /a in the lower layers above layer N and find the indexed dir /a from
+ * layer 1. If that improvement is made, then the check for "layer N connected"
+ * will need to verify there are no redirects in lower layers above N. In the
+ * example above, /a will be "layer 2 connectable". However, if layer 2 dir /a
+ * is a target of a layer 1 redirect, then /a will NOT be "layer 2 connectable":
+ *
+ * layer 1: /A (redirect = /a)
+ * layer 2: /a/b/c
+ */
+
+/* Return the lowest layer for encoding a connectable file handle */
+static int ovl_connectable_layer(struct dentry *dentry)
+{
+        struct ovl_entry *oe = OVL_E(dentry);
+
+        /* We can get overlay root from root of any layer */
+        if (dentry == dentry->d_sb->s_root)
+                return oe->numlower;
+
+        /*
+         * If it's an unindexed merge dir, then it's not connectable with any
+         * lower layer
+         */
+        if (ovl_dentry_upper(dentry) &&
+            !ovl_test_flag(OVL_INDEX, d_inode(dentry)))
+                return 0;
+
+        /* We can get upper/overlay path from indexed/lower dentry */
+        return oe->lowerstack[0].layer->idx;
+}
+
+/*
+ * @dentry is "connected" if all ancestors up to root or a "connected" ancestor
+ * have the same uppermost lower layer as the origin's layer. We may need to
+ * copy up a "connectable" ancestor to make it "connected". A "connected" dentry
+ * cannot become non "connected", so cache positive result in dentry flags.
+ *
+ * Return the connected origin layer or < 0 on error.
+ */
+static int ovl_connect_layer(struct dentry *dentry)
+{
+        struct dentry *next, *parent = NULL;
+        int origin_layer;
+        int err = 0;
+
+        if (WARN_ON(dentry == dentry->d_sb->s_root) ||
+            WARN_ON(!ovl_dentry_lower(dentry)))
+                return -EIO;
+
+        origin_layer = OVL_E(dentry)->lowerstack[0].layer->idx;
+        if (ovl_dentry_test_flag(OVL_E_CONNECTED, dentry))
+                return origin_layer;
+
+        /* Find the topmost origin layer connectable ancestor of @dentry */
+        next = dget(dentry);
+        for (;;) {
+                parent = dget_parent(next);
+                if (WARN_ON(parent == next)) {
+                        err = -EIO;
+                        break;
+                }
+
+                /*
+                 * If @parent is not origin layer connectable, then copy up
+                 * @next which is origin layer connectable and we are done.
+                 */
+                if (ovl_connectable_layer(parent) < origin_layer) {
+                        err = ovl_encode_maybe_copy_up(next);
+                        break;
+                }
+
+                /* If @parent is connected or indexed we are done */
+                if (ovl_dentry_test_flag(OVL_E_CONNECTED, parent) ||
+                    ovl_test_flag(OVL_INDEX, d_inode(parent)))
+                        break;
+
+                dput(next);
+                next = parent;
+        }
+
+        dput(parent);
+        dput(next);
+
+        if (!err)
+                ovl_dentry_set_flag(OVL_E_CONNECTED, dentry);
+
+        return err ?: origin_layer;
+}
+
 /*
  * We only need to encode origin if there is a chance that the same object was
  * encoded pre copy up and then we need to stay consistent with the same
@@ -41,73 +177,59 @@
  * L = lower file handle
  *
  * (*) Connecting an overlay dir from real lower dentry is not always
- * possible when there are redirects in lower layers. To mitigate this case,
- * we copy up the lower dir first and then encode an upper dir file handle.
+ * possible when there are redirects in lower layers and non-indexed merge dirs.
+ * To mitigate those case, we may copy up the lower dir ancestor before encode
+ * a lower dir file handle.
+ *
+ * Return 0 for upper file handle, > 0 for lower file handle or < 0 on error.
  */
-static bool ovl_should_encode_origin(struct dentry *dentry)
+static int ovl_check_encode_origin(struct dentry *dentry)
 {
         struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
 
+        /* Upper file handle for pure upper */
         if (!ovl_dentry_lower(dentry))
-                return false;
+                return 0;
 
         /*
-         * Decoding a merge dir, whose origin's parent is under a redirected
-         * lower dir is not always possible. As a simple aproximation, we do
-         * not encode lower dir file handles when overlay has multiple lower
-         * layers and origin is below the topmost lower layer.
+         * Upper file handle for non-indexed upper.
          *
-         * TODO: copy up only the parent that is under redirected lower.
+         * Root is never indexed, so if there's an upper layer, encode upper for
+         * root.
          */
-        if (d_is_dir(dentry) && ofs->upper_mnt &&
-            OVL_E(dentry)->lowerstack[0].layer->idx > 1)
-                return false;
-
-        /* Decoding a non-indexed upper from origin is not implemented */
         if (ovl_dentry_upper(dentry) &&
             !ovl_test_flag(OVL_INDEX, d_inode(dentry)))
-                return false;
-
-        return true;
-}
-
-static int ovl_encode_maybe_copy_up(struct dentry *dentry)
-{
-        int err;
-
-        if (ovl_dentry_upper(dentry))
                 return 0;
 
-        err = ovl_want_write(dentry);
-        if (err)
-                return err;
-
-        err = ovl_copy_up(dentry);
+        /*
+         * Decoding a merge dir, whose origin's ancestor is under a redirected
+         * lower dir or under a non-indexed upper is not always possible.
+         * ovl_connect_layer() will try to make origin's layer "connected" by
+         * copying up a "connectable" ancestor.
+         */
+        if (d_is_dir(dentry) && ofs->upper_mnt)
+                return ovl_connect_layer(dentry);
 
-        ovl_drop_write(dentry);
-        return err;
+        /* Lower file handle for indexed and non-upper dir/non-dir */
+        return 1;
 }
 
 static int ovl_d_to_fh(struct dentry *dentry, char *buf, int buflen)
 {
-        struct dentry *origin = ovl_dentry_lower(dentry);
         struct ovl_fh *fh = NULL;
-        int err;
+        int err, enc_lower;
 
         /*
-         * If we should not encode a lower dir file handle, copy up and encode
-         * an upper dir file handle.
+         * Check if we should encode a lower or upper file handle and maybe
+         * copy up an ancestor to make lower file handle connectable.
          */
-        if (!ovl_should_encode_origin(dentry)) {
-                err = ovl_encode_maybe_copy_up(dentry);
-                if (err)
-                        goto fail;
-
-                origin = NULL;
-        }
+        err = enc_lower = ovl_check_encode_origin(dentry);
+        if (enc_lower < 0)
+                goto fail;
 
-        /* Encode an upper or origin file handle */
-        fh = ovl_encode_fh(origin ?: ovl_dentry_upper(dentry), !origin);
+        /* Encode an upper or lower file handle */
+        fh = ovl_encode_fh(enc_lower ? ovl_dentry_lower(dentry) :
+                                       ovl_dentry_upper(dentry), !enc_lower);
         err = PTR_ERR(fh);
         if (IS_ERR(fh))
                 goto fail;
@@ -355,8 +477,8 @@ static struct dentry *ovl_lookup_real_inode(struct super_block *sb,
                 dput(upper);
         }
 
-        if (!this)
-                return NULL;
+        if (IS_ERR_OR_NULL(this))
+                return this;
 
         if (WARN_ON(ovl_dentry_real_at(this, layer->idx) != real)) {
                 dput(this);
@@ -498,7 +620,7 @@ static struct dentry *ovl_lookup_real(struct super_block *sb,
                         if (err == -ECHILD) {
                                 this = ovl_lookup_real_ancestor(sb, real,
                                                                 layer);
-                                err = IS_ERR(this) ? PTR_ERR(this) : 0;
+                                err = PTR_ERR_OR_ZERO(this);
                         }
                         if (!err) {
                                 dput(connected);
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index fcd97b783fa1..3b1bd469accd 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -669,38 +669,59 @@ struct inode *ovl_lookup_inode(struct super_block *sb, struct dentry *real,
         return inode;
 }
 
+/*
+ * Does overlay inode need to be hashed by lower inode?
+ */
+static bool ovl_hash_bylower(struct super_block *sb, struct dentry *upper,
+                             struct dentry *lower, struct dentry *index)
+{
+        struct ovl_fs *ofs = sb->s_fs_info;
+
+        /* No, if pure upper */
+        if (!lower)
+                return false;
+
+        /* Yes, if already indexed */
+        if (index)
+                return true;
+
+        /* Yes, if won't be copied up */
+        if (!ofs->upper_mnt)
+                return true;
+
+        /* No, if lower hardlink is or will be broken on copy up */
+        if ((upper || !ovl_indexdir(sb)) &&
+            !d_is_dir(lower) && d_inode(lower)->i_nlink > 1)
+                return false;
+
+        /* No, if non-indexed upper with NFS export */
+        if (sb->s_export_op && upper)
+                return false;
+
+        /* Otherwise, hash by lower inode for fsnotify */
+        return true;
+}
+
 struct inode *ovl_get_inode(struct super_block *sb, struct dentry *upperdentry,
                             struct dentry *lowerdentry, struct dentry *index,
                             unsigned int numlower)
 {
-        struct ovl_fs *ofs = sb->s_fs_info;
         struct inode *realinode = upperdentry ? d_inode(upperdentry) : NULL;
         struct inode *inode;
-        /* Already indexed or could be indexed on copy up? */
-        bool indexed = (index || (ovl_indexdir(sb) && !upperdentry));
-        struct dentry *origin = indexed ? lowerdentry : NULL;
+        bool bylower = ovl_hash_bylower(sb, upperdentry, lowerdentry, index);
         bool is_dir;
 
-        if (WARN_ON(upperdentry && indexed && !lowerdentry))
-                return ERR_PTR(-EIO);
-
         if (!realinode)
                 realinode = d_inode(lowerdentry);
 
         /*
-         * Copy up origin (lower) may exist for non-indexed non-dir upper, but
-         * we must not use lower as hash key in that case.
-         * Hash non-dir that is or could be indexed by origin inode.
-         * Hash dir that is or could be merged by origin inode.
-         * Hash pure upper and non-indexed non-dir by upper inode.
-         * Hash non-indexed dir by upper inode for NFS export.
+         * Copy up origin (lower) may exist for non-indexed upper, but we must
+         * not use lower as hash key if this is a broken hardlink.
          */
         is_dir = S_ISDIR(realinode->i_mode);
-        if (is_dir && (indexed || !sb->s_export_op || !ofs->upper_mnt))
-                origin = lowerdentry;
-
-        if (upperdentry || origin) {
-                struct inode *key = d_inode(origin ?: upperdentry);
+        if (upperdentry || bylower) {
+                struct inode *key = d_inode(bylower ? lowerdentry :
+                                                      upperdentry);
                 unsigned int nlink = is_dir ? 1 : realinode->i_nlink;
 
                 inode = iget5_locked(sb, (unsigned long) key,
@@ -728,6 +749,7 @@ struct inode *ovl_get_inode(struct super_block *sb, struct dentry *upperdentry,
                         nlink = ovl_get_nlink(lowerdentry, upperdentry, nlink);
                 set_nlink(inode, nlink);
         } else {
+                /* Lower hardlink that will be broken on copy up */
                 inode = new_inode(sb);
                 if (!inode)
                         goto out_nomem;
diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
index de3e6da1d5a5..70fcfcc684cc 100644
--- a/fs/overlayfs/namei.c
+++ b/fs/overlayfs/namei.c
@@ -913,9 +913,6 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
                 stack[ctr].layer = lower.layer;
                 ctr++;
 
-                if (d.stop)
-                        break;
-
                 /*
                  * Following redirects can have security consequences: it's like
                  * a symlink into the lower layer without the permission checks.
@@ -933,6 +930,9 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
                         goto out_put;
                 }
 
+                if (d.stop)
+                        break;
+
                 if (d.redirect && d.redirect[0] == '/' && poe != roe) {
                         poe = roe;
                         /* Find the current layer on the root dentry */
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index 0df25a9c94bd..225ff1171147 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -40,6 +40,7 @@ enum ovl_inode_flag {
 enum ovl_entry_flag {
         OVL_E_UPPER_ALIAS,
         OVL_E_OPAQUE,
+        OVL_E_CONNECTED,
 };
 
 /*
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 9ee37c76091d..7c24619ae7fc 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -1359,6 +1359,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
 
         /* Root is always merge -> can have whiteouts */
         ovl_set_flag(OVL_WHITEOUTS, d_inode(root_dentry));
+        ovl_dentry_set_flag(OVL_E_CONNECTED, root_dentry);
         ovl_inode_init(d_inode(root_dentry), upperpath.dentry,
                        ovl_dentry_lower(root_dentry));
 
diff --git a/fs/sysfs/symlink.c b/fs/sysfs/symlink.c
index 8664db25a9a6..215c225b2ca1 100644
--- a/fs/sysfs/symlink.c
+++ b/fs/sysfs/symlink.c
@@ -106,6 +106,7 @@ int sysfs_create_link_nowarn(struct kobject *kobj, struct kobject *target,
 {
         return sysfs_do_create_link(kobj, target, name, 0);
 }
+EXPORT_SYMBOL_GPL(sysfs_create_link_nowarn);
 
 /**
  *      sysfs_delete_link - remove symlink in object's directory.
diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index 66e1edbfb2b2..046469fcc1b8 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -955,15 +955,29 @@ static inline bool imap_needs_alloc(struct inode *inode,
                 (IS_DAX(inode) && imap->br_state == XFS_EXT_UNWRITTEN);
 }
 
+static inline bool needs_cow_for_zeroing(struct xfs_bmbt_irec *imap, int nimaps)
+{
+        return nimaps &&
+                imap->br_startblock != HOLESTARTBLOCK &&
+                imap->br_state != XFS_EXT_UNWRITTEN;
+}
+
 static inline bool need_excl_ilock(struct xfs_inode *ip, unsigned flags)
 {
         /*
-         * COW writes will allocate delalloc space, so we need to make sure
-         * to take the lock exclusively here.
+         * COW writes may allocate delalloc space or convert unwritten COW
+         * extents, so we need to make sure to take the lock exclusively here.
          */
         if (xfs_is_reflink_inode(ip) && (flags & (IOMAP_WRITE | IOMAP_ZERO)))
                 return true;
-        if ((flags & IOMAP_DIRECT) && (flags & IOMAP_WRITE))
+
+        /*
+         * Extents not yet cached requires exclusive access, don't block.
+         * This is an opencoded xfs_ilock_data_map_shared() to cater for the
+         * non-blocking behaviour.
+         */
+        if (ip->i_d.di_format == XFS_DINODE_FMT_BTREE &&
+            !(ip->i_df.if_flags & XFS_IFEXTENTS))
                 return true;
         return false;
 }
@@ -993,16 +1007,18 @@ xfs_file_iomap_begin(
                 return xfs_file_iomap_begin_delay(inode, offset, length, iomap);
         }
 
-        if (need_excl_ilock(ip, flags)) {
+        if (need_excl_ilock(ip, flags))
                 lockmode = XFS_ILOCK_EXCL;
-                xfs_ilock(ip, XFS_ILOCK_EXCL);
-        } else {
-                lockmode = xfs_ilock_data_map_shared(ip);
-        }
+        else
+                lockmode = XFS_ILOCK_SHARED;
 
-        if ((flags & IOMAP_NOWAIT) && !(ip->i_df.if_flags & XFS_IFEXTENTS)) {
-                error = -EAGAIN;
-                goto out_unlock;
+        if (flags & IOMAP_NOWAIT) {
+                if (!(ip->i_df.if_flags & XFS_IFEXTENTS))
+                        return -EAGAIN;
+                if (!xfs_ilock_nowait(ip, lockmode))
+                        return -EAGAIN;
+        } else {
+                xfs_ilock(ip, lockmode);
         }
 
         ASSERT(offset <= mp->m_super->s_maxbytes);
@@ -1024,7 +1040,9 @@ xfs_file_iomap_begin(
                         goto out_unlock;
         }
 
-        if ((flags & (IOMAP_WRITE | IOMAP_ZERO)) && xfs_is_reflink_inode(ip)) {
+        if (xfs_is_reflink_inode(ip) &&
+            ((flags & IOMAP_WRITE) ||
+             ((flags & IOMAP_ZERO) && needs_cow_for_zeroing(&imap, nimaps)))) {
                 if (flags & IOMAP_DIRECT) {
                         /*
                          * A reflinked inode will result in CoW alloc.