Merge branch 'bugfixes' into linux-next

* bugfixes:
  NFS: Don't reset pg_moreio in __nfs_pageio_add_request
  NFS: Remove 2 unused variables
  nfs: handle multiple reqs in nfs_wb_page_cancel
  nfs: handle multiple reqs in nfs_page_async_flush
  nfs: change find_request to find_head_request
  nfs: nfs_page should take a ref on the head req
  nfs: mark nfs_page reqs with flag for extra ref
  nfs: only show Posix ACLs in listxattr if actually present

Conflicts:
	fs/nfs/write.c

6 files changed, 343 insertions, 62 deletions

diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
index 2a3293a5dda0..65ef6e00deee 100644
--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -749,14 +749,12 @@ static void nfs_direct_write_completion(struct nfs_pgio_header *hdr)
         spin_unlock(&dreq->lock);
 
         while (!list_empty(&hdr->pages)) {
-                bool do_destroy = true;
 
                 req = nfs_list_entry(hdr->pages.next);
                 nfs_list_remove_request(req);
                 if (request_commit) {
                         kref_get(&req->wb_kref);
                         nfs_mark_request_commit(req, hdr->lseg, &cinfo);
-                        do_destroy = false;
                 }
                 nfs_unlock_and_release_request(req);
         }
diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index da36257628c5..2f19e8392eb3 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -244,6 +244,7 @@ void nfs_pgio_data_destroy(struct nfs_pgio_header *);
 int nfs_generic_pgio(struct nfs_pageio_descriptor *, struct nfs_pgio_header *);
 int nfs_initiate_pgio(struct rpc_clnt *, struct nfs_pgio_header *,
                       const struct rpc_call_ops *, int, int);
+void nfs_free_request(struct nfs_page *req);
 
 static inline void nfs_iocounter_init(struct nfs_io_counter *c)
 {
diff --git a/fs/nfs/nfs3acl.c b/fs/nfs/nfs3acl.c
index 871d6eda8dba..8f854dde4150 100644
--- a/fs/nfs/nfs3acl.c
+++ b/fs/nfs/nfs3acl.c
@@ -247,3 +247,46 @@ const struct xattr_handler *nfs3_xattr_handlers[] = {
         &posix_acl_default_xattr_handler,
         NULL,
 };
+
+static int
+nfs3_list_one_acl(struct inode *inode, int type, const char *name, void *data,
+                size_t size, ssize_t *result)
+{
+        struct posix_acl *acl;
+        char *p = data + *result;
+
+        acl = get_acl(inode, type);
+        if (!acl)
+                return 0;
+
+        posix_acl_release(acl);
+
+        *result += strlen(name);
+        *result += 1;
+        if (!size)
+                return 0;
+        if (*result > size)
+                return -ERANGE;
+
+        strcpy(p, name);
+        return 0;
+}
+
+ssize_t
+nfs3_listxattr(struct dentry *dentry, char *data, size_t size)
+{
+        struct inode *inode = dentry->d_inode;
+        ssize_t result = 0;
+        int error;
+
+        error = nfs3_list_one_acl(inode, ACL_TYPE_ACCESS,
+                        POSIX_ACL_XATTR_ACCESS, data, size, &result);
+        if (error)
+                return error;
+
+        error = nfs3_list_one_acl(inode, ACL_TYPE_DEFAULT,
+                        POSIX_ACL_XATTR_DEFAULT, data, size, &result);
+        if (error)
+                return error;
+        return result;
+}
diff --git a/fs/nfs/nfs3proc.c b/fs/nfs/nfs3proc.c
index 854959db0e5d..809670eba52a 100644
--- a/fs/nfs/nfs3proc.c
+++ b/fs/nfs/nfs3proc.c
@@ -888,7 +888,7 @@ static const struct inode_operations nfs3_dir_inode_operations = {
         .getattr        = nfs_getattr,
         .setattr        = nfs_setattr,
 #ifdef CONFIG_NFS_V3_ACL
-        .listxattr      = generic_listxattr,
+        .listxattr      = nfs3_listxattr,
         .getxattr       = generic_getxattr,
         .setxattr       = generic_setxattr,
         .removexattr    = generic_removexattr,
@@ -902,7 +902,7 @@ static const struct inode_operations nfs3_file_inode_operations = {
         .getattr        = nfs_getattr,
         .setattr        = nfs_setattr,
 #ifdef CONFIG_NFS_V3_ACL
-        .listxattr      = generic_listxattr,
+        .listxattr      = nfs3_listxattr,
         .getxattr       = generic_getxattr,
         .setxattr       = generic_setxattr,
         .removexattr    = generic_removexattr,
diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index 6e2c0bce5926..e76a40e298f2 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -29,8 +29,6 @@
 static struct kmem_cache *nfs_page_cachep;
 static const struct rpc_call_ops nfs_pgio_common_ops;
 
-static void nfs_free_request(struct nfs_page *);
-
 static bool nfs_pgarray_set(struct nfs_page_array *p, unsigned int pagecount)
 {
         p->npages = pagecount;
@@ -239,20 +237,28 @@ nfs_page_group_init(struct nfs_page *req, struct nfs_page *prev)
         WARN_ON_ONCE(prev == req);
 
         if (!prev) {
+                /* a head request */
                 req->wb_head = req;
                 req->wb_this_page = req;
         } else {
+                /* a subrequest */
                 WARN_ON_ONCE(prev->wb_this_page != prev->wb_head);
                 WARN_ON_ONCE(!test_bit(PG_HEADLOCK, &prev->wb_head->wb_flags));
                 req->wb_head = prev->wb_head;
                 req->wb_this_page = prev->wb_this_page;
                 prev->wb_this_page = req;
 
+                /* All subrequests take a ref on the head request until
+                 * nfs_page_group_destroy is called */
+                kref_get(&req->wb_head->wb_kref);
+
                 /* grab extra ref if head request has extra ref from
                  * the write/commit path to handle handoff between write
                  * and commit lists */
-                if (test_bit(PG_INODE_REF, &prev->wb_head->wb_flags))
+                if (test_bit(PG_INODE_REF, &prev->wb_head->wb_flags)) {
+                        set_bit(PG_INODE_REF, &req->wb_flags);
                         kref_get(&req->wb_kref);
+                }
         }
 }
 
@@ -269,6 +275,10 @@ nfs_page_group_destroy(struct kref *kref)
         struct nfs_page *req = container_of(kref, struct nfs_page, wb_kref);
         struct nfs_page *tmp, *next;
 
+        /* subrequests must release the ref on the head request */
+        if (req->wb_head != req)
+                nfs_release_request(req->wb_head);
+
         if (!nfs_page_group_sync_on_bit(req, PG_TEARDOWN))
                 return;
 
@@ -394,7 +404,7 @@ static void nfs_clear_request(struct nfs_page *req)
  *
  * Note: Should never be called with the spinlock held!
  */
-static void nfs_free_request(struct nfs_page *req)
+void nfs_free_request(struct nfs_page *req)
 {
         WARN_ON_ONCE(req->wb_this_page != req);
 
@@ -868,7 +878,6 @@ static int __nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
                         nfs_pageio_doio(desc);
                         if (desc->pg_error < 0)
                                 return 0;
-                        desc->pg_moreio = 0;
                         if (desc->pg_recoalesce)
                                 return 0;
                         /* retry add_request for this subreq */
@@ -915,6 +924,7 @@ static int nfs_do_recoalesce(struct nfs_pageio_descriptor *desc)
                 desc->pg_count = 0;
                 desc->pg_base = 0;
                 desc->pg_recoalesce = 0;
+                desc->pg_moreio = 0;
 
                 while (!list_empty(&head)) {
                         struct nfs_page *req;
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 8534ee5c207d..d357728ed8ba 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -46,6 +46,7 @@ static const struct rpc_call_ops nfs_commit_ops;
 static const struct nfs_pgio_completion_ops nfs_async_write_completion_ops;
 static const struct nfs_commit_completion_ops nfs_commit_completion_ops;
 static const struct nfs_rw_ops nfs_rw_write_ops;
+static void nfs_clear_request_commit(struct nfs_page *req);
 
 static struct kmem_cache *nfs_wdata_cachep;
 static mempool_t *nfs_wdata_mempool;
@@ -91,8 +92,15 @@ static void nfs_context_set_write_error(struct nfs_open_context *ctx, int error)
         set_bit(NFS_CONTEXT_ERROR_WRITE, &ctx->flags);
 }
 
+/*
+ * nfs_page_find_head_request_locked - find head request associated with @page
+ *
+ * must be called while holding the inode lock.
+ *
+ * returns matching head request with reference held, or NULL if not found.
+ */
 static struct nfs_page *
-nfs_page_find_request_locked(struct nfs_inode *nfsi, struct page *page)
+nfs_page_find_head_request_locked(struct nfs_inode *nfsi, struct page *page)
 {
         struct nfs_page *req = NULL;
 
@@ -104,25 +112,33 @@ nfs_page_find_request_locked(struct nfs_inode *nfsi, struct page *page)
                 /* Linearly search the commit list for the correct req */
                 list_for_each_entry_safe(freq, t, &nfsi->commit_info.list, wb_list) {
                         if (freq->wb_page == page) {
-                                req = freq;
+                                req = freq->wb_head;
                                 break;
                         }
                 }
         }
 
-        if (req)
+        if (req) {
+                WARN_ON_ONCE(req->wb_head != req);
+
                 kref_get(&req->wb_kref);
+        }
 
         return req;
 }
 
-static struct nfs_page *nfs_page_find_request(struct page *page)
+/*
+ * nfs_page_find_head_request - find head request associated with @page
+ *
+ * returns matching head request with reference held, or NULL if not found.
+ */
+static struct nfs_page *nfs_page_find_head_request(struct page *page)
 {
         struct inode *inode = page_file_mapping(page)->host;
         struct nfs_page *req = NULL;
 
         spin_lock(&inode->i_lock);
-        req = nfs_page_find_request_locked(NFS_I(inode), page);
+        req = nfs_page_find_head_request_locked(NFS_I(inode), page);
         spin_unlock(&inode->i_lock);
         return req;
 }
@@ -274,36 +290,246 @@ static void nfs_end_page_writeback(struct nfs_page *req)
                 clear_bdi_congested(&nfss->backing_dev_info, BLK_RW_ASYNC);
 }
 
-static struct nfs_page *nfs_find_and_lock_request(struct page *page, bool nonblock)
+
+/* nfs_page_group_clear_bits
+ *   @req - an nfs request
+ * clears all page group related bits from @req
+ */
+static void
+nfs_page_group_clear_bits(struct nfs_page *req)
+{
+        clear_bit(PG_TEARDOWN, &req->wb_flags);
+        clear_bit(PG_UNLOCKPAGE, &req->wb_flags);
+        clear_bit(PG_UPTODATE, &req->wb_flags);
+        clear_bit(PG_WB_END, &req->wb_flags);
+        clear_bit(PG_REMOVE, &req->wb_flags);
+}
+
+
+/*
+ * nfs_unroll_locks_and_wait -  unlock all newly locked reqs and wait on @req
+ *
+ * this is a helper function for nfs_lock_and_join_requests
+ *
+ * @inode - inode associated with request page group, must be holding inode lock
+ * @head  - head request of page group, must be holding head lock
+ * @req   - request that couldn't lock and needs to wait on the req bit lock
+ * @nonblock - if true, don't actually wait
+ *
+ * NOTE: this must be called holding page_group bit lock and inode spin lock
+ *       and BOTH will be released before returning.
+ *
+ * returns 0 on success, < 0 on error.
+ */
+static int
+nfs_unroll_locks_and_wait(struct inode *inode, struct nfs_page *head,
+                          struct nfs_page *req, bool nonblock)
+        __releases(&inode->i_lock)
+{
+        struct nfs_page *tmp;
+        int ret;
+
+        /* relinquish all the locks successfully grabbed this run */
+        for (tmp = head ; tmp != req; tmp = tmp->wb_this_page)
+                nfs_unlock_request(tmp);
+
+        WARN_ON_ONCE(test_bit(PG_TEARDOWN, &req->wb_flags));
+
+        /* grab a ref on the request that will be waited on */
+        kref_get(&req->wb_kref);
+
+        nfs_page_group_unlock(head);
+        spin_unlock(&inode->i_lock);
+
+        /* release ref from nfs_page_find_head_request_locked */
+        nfs_release_request(head);
+
+        if (!nonblock)
+                ret = nfs_wait_on_request(req);
+        else
+                ret = -EAGAIN;
+        nfs_release_request(req);
+
+        return ret;
+}
+
+/*
+ * nfs_destroy_unlinked_subrequests - destroy recently unlinked subrequests
+ *
+ * @destroy_list - request list (using wb_this_page) terminated by @old_head
+ * @old_head - the old head of the list
+ *
+ * All subrequests must be locked and removed from all lists, so at this point
+ * they are only "active" in this function, and possibly in nfs_wait_on_request
+ * with a reference held by some other context.
+ */
+static void
+nfs_destroy_unlinked_subrequests(struct nfs_page *destroy_list,
+                                 struct nfs_page *old_head)
+{
+        while (destroy_list) {
+                struct nfs_page *subreq = destroy_list;
+
+                destroy_list = (subreq->wb_this_page == old_head) ?
+                                   NULL : subreq->wb_this_page;
+
+                WARN_ON_ONCE(old_head != subreq->wb_head);
+
+                /* make sure old group is not used */
+                subreq->wb_head = subreq;
+                subreq->wb_this_page = subreq;
+
+                nfs_clear_request_commit(subreq);
+
+                /* subreq is now totally disconnected from page group or any
+                 * write / commit lists. last chance to wake any waiters */
+                nfs_unlock_request(subreq);
+
+                if (!test_bit(PG_TEARDOWN, &subreq->wb_flags)) {
+                        /* release ref on old head request */
+                        nfs_release_request(old_head);
+
+                        nfs_page_group_clear_bits(subreq);
+
+                        /* release the PG_INODE_REF reference */
+                        if (test_and_clear_bit(PG_INODE_REF, &subreq->wb_flags))
+                                nfs_release_request(subreq);
+                        else
+                                WARN_ON_ONCE(1);
+                } else {
+                        WARN_ON_ONCE(test_bit(PG_CLEAN, &subreq->wb_flags));
+                        /* zombie requests have already released the last
+                         * reference and were waiting on the rest of the
+                         * group to complete. Since it's no longer part of a
+                         * group, simply free the request */
+                        nfs_page_group_clear_bits(subreq);
+                        nfs_free_request(subreq);
+                }
+        }
+}
+
+/*
+ * nfs_lock_and_join_requests - join all subreqs to the head req and return
+ *                              a locked reference, cancelling any pending
+ *                              operations for this page.
+ *
+ * @page - the page used to lookup the "page group" of nfs_page structures
+ * @nonblock - if true, don't block waiting for request locks
+ *
+ * This function joins all sub requests to the head request by first
+ * locking all requests in the group, cancelling any pending operations
+ * and finally updating the head request to cover the whole range covered by
+ * the (former) group.  All subrequests are removed from any write or commit
+ * lists, unlinked from the group and destroyed.
+ *
+ * Returns a locked, referenced pointer to the head request - which after
+ * this call is guaranteed to be the only request associated with the page.
+ * Returns NULL if no requests are found for @page, or a ERR_PTR if an
+ * error was encountered.
+ */
+static struct nfs_page *
+nfs_lock_and_join_requests(struct page *page, bool nonblock)
 {
         struct inode *inode = page_file_mapping(page)->host;
-        struct nfs_page *req;
+        struct nfs_page *head, *subreq;
+        struct nfs_page *destroy_list = NULL;
+        unsigned int total_bytes;
         int ret;
 
+try_again:
+        total_bytes = 0;
+
+        WARN_ON_ONCE(destroy_list);
+
         spin_lock(&inode->i_lock);
-        for (;;) {
-                req = nfs_page_find_request_locked(NFS_I(inode), page);
-                if (req == NULL)
-                        break;
-                if (nfs_lock_request(req))
-                        break;
-                /* Note: If we hold the page lock, as is the case in nfs_writepage,
-                 *       then the call to nfs_lock_request() will always
-                 *       succeed provided that someone hasn't already marked the
-                 *       request as dirty (in which case we don't care).
-                 */
+
+        /*
+         * A reference is taken only on the head request which acts as a
+         * reference to the whole page group - the group will not be destroyed
+         * until the head reference is released.
+         */
+        head = nfs_page_find_head_request_locked(NFS_I(inode), page);
+
+        if (!head) {
                 spin_unlock(&inode->i_lock);
-                if (!nonblock)
-                        ret = nfs_wait_on_request(req);
-                else
-                        ret = -EAGAIN;
-                nfs_release_request(req);
-                if (ret != 0)
+                return NULL;
+        }
+
+        /* lock each request in the page group */
+        nfs_page_group_lock(head);
+        subreq = head;
+        do {
+                /*
+                 * Subrequests are always contiguous, non overlapping
+                 * and in order. If not, it's a programming error.
+                 */
+                WARN_ON_ONCE(subreq->wb_offset !=
+                     (head->wb_offset + total_bytes));
+
+                /* keep track of how many bytes this group covers */
+                total_bytes += subreq->wb_bytes;
+
+                if (!nfs_lock_request(subreq)) {
+                        /* releases page group bit lock and
+                         * inode spin lock and all references */
+                        ret = nfs_unroll_locks_and_wait(inode, head,
+                                subreq, nonblock);
+
+                        if (ret == 0)
+                                goto try_again;
+
                         return ERR_PTR(ret);
-                spin_lock(&inode->i_lock);
+                }
+
+                subreq = subreq->wb_this_page;
+        } while (subreq != head);
+
+        /* Now that all requests are locked, make sure they aren't on any list.
+         * Commit list removal accounting is done after locks are dropped */
+        subreq = head;
+        do {
+                nfs_list_remove_request(subreq);
+                subreq = subreq->wb_this_page;
+        } while (subreq != head);
+
+        /* unlink subrequests from head, destroy them later */
+        if (head->wb_this_page != head) {
+                /* destroy list will be terminated by head */
+                destroy_list = head->wb_this_page;
+                head->wb_this_page = head;
+
+                /* change head request to cover whole range that
+                 * the former page group covered */
+                head->wb_bytes = total_bytes;
         }
+
+        /*
+         * prepare head request to be added to new pgio descriptor
+         */
+        nfs_page_group_clear_bits(head);
+
+        /*
+         * some part of the group was still on the inode list - otherwise
+         * the group wouldn't be involved in async write.
+         * grab a reference for the head request, iff it needs one.
+         */
+        if (!test_and_set_bit(PG_INODE_REF, &head->wb_flags))
+                kref_get(&head->wb_kref);
+
+        nfs_page_group_unlock(head);
+
+        /* drop lock to clear_request_commit the head req and clean up
+         * requests on destroy list */
         spin_unlock(&inode->i_lock);
-        return req;
+
+        nfs_destroy_unlinked_subrequests(destroy_list, head);
+
+        /* clean up commit list state */
+        nfs_clear_request_commit(head);
+
+        /* still holds ref on head from nfs_page_find_head_request_locked
+         * and still has lock on head from lock loop */
+        return head;
 }
 
 /*
@@ -316,7 +542,7 @@ static int nfs_page_async_flush(struct nfs_pageio_descriptor *pgio,
         struct nfs_page *req;
         int ret = 0;
 
-        req = nfs_find_and_lock_request(page, nonblock);
+        req = nfs_lock_and_join_requests(page, nonblock);
         if (!req)
                 goto out;
         ret = PTR_ERR(req);
@@ -448,7 +674,9 @@ static void nfs_inode_add_request(struct inode *inode, struct nfs_page *req)
                 set_page_private(req->wb_page, (unsigned long)req);
         }
         nfsi->npages++;
-        set_bit(PG_INODE_REF, &req->wb_flags);
+        /* this a head request for a page group - mark it as having an
+         * extra reference so sub groups can follow suit */
+        WARN_ON(test_and_set_bit(PG_INODE_REF, &req->wb_flags));
         kref_get(&req->wb_kref);
         spin_unlock(&inode->i_lock);
 }
@@ -474,7 +702,9 @@ static void nfs_inode_remove_request(struct nfs_page *req)
                 nfsi->npages--;
                 spin_unlock(&inode->i_lock);
         }
-        nfs_release_request(req);
+
+        if (test_and_clear_bit(PG_INODE_REF, &req->wb_flags))
+                nfs_release_request(req);
 }
 
 static void
@@ -636,7 +866,6 @@ static void nfs_write_completion(struct nfs_pgio_header *hdr)
 {
         struct nfs_commit_info cinfo;
         unsigned long bytes = 0;
-        bool do_destroy;
 
         if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
                 goto out;
@@ -662,7 +891,6 @@ remove_req:
 next:
                 nfs_unlock_request(req);
                 nfs_end_page_writeback(req);
-                do_destroy = !nfs_write_need_commit(hdr);
                 nfs_release_request(req);
         }
 out:
@@ -763,7 +991,7 @@ static struct nfs_page *nfs_try_to_update_request(struct inode *inode,
         spin_lock(&inode->i_lock);
 
         for (;;) {
-                req = nfs_page_find_request_locked(NFS_I(inode), page);
+                req = nfs_page_find_head_request_locked(NFS_I(inode), page);
                 if (req == NULL)
                         goto out_unlock;
 
@@ -871,7 +1099,7 @@ int nfs_flush_incompatible(struct file *file, struct page *page)
          * dropped page.
          */
         do {
-                req = nfs_page_find_request(page);
+                req = nfs_page_find_head_request(page);
                 if (req == NULL)
                         return 0;
                 l_ctx = req->wb_lock_context;
@@ -1555,27 +1783,28 @@ int nfs_wb_page_cancel(struct inode *inode, struct page *page)
         struct nfs_page *req;
         int ret = 0;
 
-        for (;;) {
-                wait_on_page_writeback(page);
-                req = nfs_page_find_request(page);
-                if (req == NULL)
-                        break;
-                if (nfs_lock_request(req)) {
-                        nfs_clear_request_commit(req);
-                        nfs_inode_remove_request(req);
-                        /*
-                         * In case nfs_inode_remove_request has marked the
-                         * page as being dirty
-                         */
-                        cancel_dirty_page(page, PAGE_CACHE_SIZE);
-                        nfs_unlock_and_release_request(req);
-                        break;
-                }
-                ret = nfs_wait_on_request(req);
-                nfs_release_request(req);
-                if (ret < 0)
-                        break;
+        wait_on_page_writeback(page);
+
+        /* blocking call to cancel all requests and join to a single (head)
+         * request */
+        req = nfs_lock_and_join_requests(page, false);
+
+        if (IS_ERR(req)) {
+                ret = PTR_ERR(req);
+        } else if (req) {
+                /* all requests from this page have been cancelled by
+                 * nfs_lock_and_join_requests, so just remove the head
+                 * request from the inode / page_private pointer and
+                 * release it */
+                nfs_inode_remove_request(req);
+                /*
+                 * In case nfs_inode_remove_request has marked the
+                 * page as being dirty
+                 */
+                cancel_dirty_page(page, PAGE_CACHE_SIZE);
+                nfs_unlock_and_release_request(req);
         }
+
         return ret;
 }