new helper: iov_iter_get_pages_alloc()

same as iov_iter_get_pages(), except that pages array is allocated
(kmalloc if possible, vmalloc if that fails) and left for caller to
free.  Lustre and NFS ->direct_IO() switched to it.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 88 insertions, 202 deletions

diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
index 1d34f454989e..b122fe21fea0 100644
--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -322,60 +322,37 @@ static const struct nfs_pgio_completion_ops nfs_direct_read_completion_ops = {
  * handled automatically by nfs_direct_read_result().  Otherwise, if
  * no requests have been sent, just return an error.
  */
-static ssize_t nfs_direct_read_schedule_segment(struct nfs_pageio_descriptor *desc,
-                                                const struct iovec *iov,
-                                                loff_t pos, bool uio)
-{
-        struct nfs_direct_req *dreq = desc->pg_dreq;
-        struct nfs_open_context *ctx = dreq->ctx;
-        struct inode *inode = ctx->dentry->d_inode;
-        unsigned long user_addr = (unsigned long)iov->iov_base;
-        size_t count = iov->iov_len;
-        size_t rsize = NFS_SERVER(inode)->rsize;
-        unsigned int pgbase;
-        int result;
-        ssize_t started = 0;
-        struct page **pagevec = NULL;
-        unsigned int npages;
-
-        do {
-                size_t bytes;
-                int i;
 
-                pgbase = user_addr & ~PAGE_MASK;
-                bytes = min(max_t(size_t, rsize, PAGE_SIZE), count);
+static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq,
+                                              struct iov_iter *iter,
+                                              loff_t pos)
+{
+        struct nfs_pageio_descriptor desc;
+        struct inode *inode = dreq->inode;
+        ssize_t result = -EINVAL;
+        size_t requested_bytes = 0;
+        size_t rsize = max_t(size_t, NFS_SERVER(inode)->rsize, PAGE_SIZE);
 
-                result = -ENOMEM;
-                npages = nfs_page_array_len(pgbase, bytes);
-                if (!pagevec)
-                        pagevec = kmalloc(npages * sizeof(struct page *),
-                                          GFP_KERNEL);
-                if (!pagevec)
-                        break;
-                if (uio) {
-                        down_read(&current->mm->mmap_sem);
-                        result = get_user_pages(current, current->mm, user_addr,
-                                        npages, 1, 0, pagevec, NULL);
-                        up_read(&current->mm->mmap_sem);
-                        if (result < 0)
-                                break;
-                } else {
-                        WARN_ON(npages != 1);
-                        result = get_kernel_page(user_addr, 1, pagevec);
-                        if (WARN_ON(result != 1))
-                                break;
-                }
+        NFS_PROTO(dreq->inode)->read_pageio_init(&desc, dreq->inode,
+                             &nfs_direct_read_completion_ops);
+        get_dreq(dreq);
+        desc.pg_dreq = dreq;
+        atomic_inc(&inode->i_dio_count);
 
-                if ((unsigned)result < npages) {
-                        bytes = result * PAGE_SIZE;
-                        if (bytes <= pgbase) {
-                                nfs_direct_release_pages(pagevec, result);
-                                break;
-                        }
-                        bytes -= pgbase;
-                        npages = result;
-                }
+        while (iov_iter_count(iter)) {
+                struct page **pagevec;
+                size_t bytes;
+                size_t pgbase;
+                unsigned npages, i;
 
+                result = iov_iter_get_pages_alloc(iter, &pagevec, 
+                                                  rsize, &pgbase);
+                if (result < 0)
+                        break;
+        
+                bytes = result;
+                iov_iter_advance(iter, bytes);
+                npages = (result + pgbase + PAGE_SIZE - 1) / PAGE_SIZE;
                 for (i = 0; i < npages; i++) {
                         struct nfs_page *req;
                         unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase);
@@ -389,55 +366,21 @@ static ssize_t nfs_direct_read_schedule_segment(struct nfs_pageio_descriptor *de
                         }
                         req->wb_index = pos >> PAGE_SHIFT;
                         req->wb_offset = pos & ~PAGE_MASK;
-                        if (!nfs_pageio_add_request(desc, req)) {
-                                result = desc->pg_error;
+                        if (!nfs_pageio_add_request(&desc, req)) {
+                                result = desc.pg_error;
                                 nfs_release_request(req);
                                 break;
                         }
                         pgbase = 0;
                         bytes -= req_len;
-                        started += req_len;
-                        user_addr += req_len;
+                        requested_bytes += req_len;
                         pos += req_len;
-                        count -= req_len;
                         dreq->bytes_left -= req_len;
                 }
-                /* The nfs_page now hold references to these pages */
                 nfs_direct_release_pages(pagevec, npages);
-        } while (count != 0 && result >= 0);
-
-        kfree(pagevec);
-
-        if (started)
-                return started;
-        return result < 0 ? (ssize_t) result : -EFAULT;
-}
-
-static ssize_t nfs_direct_read_schedule_iovec(struct nfs_direct_req *dreq,
-                                              struct iov_iter *iter,
-                                              loff_t pos, bool uio)
-{
-        struct nfs_pageio_descriptor desc;
-        struct inode *inode = dreq->inode;
-        ssize_t result = -EINVAL;
-        size_t requested_bytes = 0;
-        unsigned long seg;
-
-        NFS_PROTO(dreq->inode)->read_pageio_init(&desc, dreq->inode,
-                             &nfs_direct_read_completion_ops);
-        get_dreq(dreq);
-        desc.pg_dreq = dreq;
-        atomic_inc(&inode->i_dio_count);
-
-        for (seg = 0; seg < iter->nr_segs; seg++) {
-                const struct iovec *vec = &iter->iov[seg];
-                result = nfs_direct_read_schedule_segment(&desc, vec, pos, uio);
+                kvfree(pagevec);
                 if (result < 0)
                         break;
-                requested_bytes += result;
-                if ((size_t)result < vec->iov_len)
-                        break;
-                pos += vec->iov_len;
         }
 
         nfs_pageio_complete(&desc);
@@ -521,7 +464,7 @@ ssize_t nfs_file_direct_read(struct kiocb *iocb, struct iov_iter *iter,
                 dreq->iocb = iocb;
 
         NFS_I(inode)->read_io += count;
-        result = nfs_direct_read_schedule_iovec(dreq, iter, pos, uio);
+        result = nfs_direct_read_schedule_iovec(dreq, iter, pos);
 
         mutex_unlock(&inode->i_mutex);
 
@@ -677,109 +620,6 @@ static void nfs_direct_write_complete(struct nfs_direct_req *dreq, struct inode
 }
 #endif
 
-/*
- * NB: Return the value of the first error return code.  Subsequent
- *     errors after the first one are ignored.
- */
-/*
- * For each wsize'd chunk of the user's buffer, dispatch an NFS WRITE
- * operation.  If nfs_writedata_alloc() or get_user_pages() fails,
- * bail and stop sending more writes.  Write length accounting is
- * handled automatically by nfs_direct_write_result().  Otherwise, if
- * no requests have been sent, just return an error.
- */
-static ssize_t nfs_direct_write_schedule_segment(struct nfs_pageio_descriptor *desc,
-                                                 const struct iovec *iov,
-                                                 loff_t pos, bool uio)
-{
-        struct nfs_direct_req *dreq = desc->pg_dreq;
-        struct nfs_open_context *ctx = dreq->ctx;
-        struct inode *inode = ctx->dentry->d_inode;
-        unsigned long user_addr = (unsigned long)iov->iov_base;
-        size_t count = iov->iov_len;
-        size_t wsize = NFS_SERVER(inode)->wsize;
-        unsigned int pgbase;
-        int result;
-        ssize_t started = 0;
-        struct page **pagevec = NULL;
-        unsigned int npages;
-
-        do {
-                size_t bytes;
-                int i;
-
-                pgbase = user_addr & ~PAGE_MASK;
-                bytes = min(max_t(size_t, wsize, PAGE_SIZE), count);
-
-                result = -ENOMEM;
-                npages = nfs_page_array_len(pgbase, bytes);
-                if (!pagevec)
-                        pagevec = kmalloc(npages * sizeof(struct page *), GFP_KERNEL);
-                if (!pagevec)
-                        break;
-
-                if (uio) {
-                        down_read(&current->mm->mmap_sem);
-                        result = get_user_pages(current, current->mm, user_addr,
-                                                npages, 0, 0, pagevec, NULL);
-                        up_read(&current->mm->mmap_sem);
-                        if (result < 0)
-                                break;
-                } else {
-                        WARN_ON(npages != 1);
-                        result = get_kernel_page(user_addr, 0, pagevec);
-                        if (WARN_ON(result != 1))
-                                break;
-                }
-
-                if ((unsigned)result < npages) {
-                        bytes = result * PAGE_SIZE;
-                        if (bytes <= pgbase) {
-                                nfs_direct_release_pages(pagevec, result);
-                                break;
-                        }
-                        bytes -= pgbase;
-                        npages = result;
-                }
-
-                for (i = 0; i < npages; i++) {
-                        struct nfs_page *req;
-                        unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase);
-
-                        req = nfs_create_request(dreq->ctx, dreq->inode,
-                                                 pagevec[i],
-                                                 pgbase, req_len);
-                        if (IS_ERR(req)) {
-                                result = PTR_ERR(req);
-                                break;
-                        }
-                        nfs_lock_request(req);
-                        req->wb_index = pos >> PAGE_SHIFT;
-                        req->wb_offset = pos & ~PAGE_MASK;
-                        if (!nfs_pageio_add_request(desc, req)) {
-                                result = desc->pg_error;
-                                nfs_unlock_and_release_request(req);
-                                break;
-                        }
-                        pgbase = 0;
-                        bytes -= req_len;
-                        started += req_len;
-                        user_addr += req_len;
-                        pos += req_len;
-                        count -= req_len;
-                        dreq->bytes_left -= req_len;
-                }
-                /* The nfs_page now hold references to these pages */
-                nfs_direct_release_pages(pagevec, npages);
-        } while (count != 0 && result >= 0);
-
-        kfree(pagevec);
-
-        if (started)
-                return started;
-        return result < 0 ? (ssize_t) result : -EFAULT;
-}
-
 static void nfs_direct_write_completion(struct nfs_pgio_header *hdr)
 {
         struct nfs_direct_req *dreq = hdr->dreq;
@@ -859,15 +699,27 @@ static const struct nfs_pgio_completion_ops nfs_direct_write_completion_ops = {
         .completion = nfs_direct_write_completion,
 };
 
+
+/*
+ * NB: Return the value of the first error return code.  Subsequent
+ *     errors after the first one are ignored.
+ */
+/*
+ * For each wsize'd chunk of the user's buffer, dispatch an NFS WRITE
+ * operation.  If nfs_writedata_alloc() or get_user_pages() fails,
+ * bail and stop sending more writes.  Write length accounting is
+ * handled automatically by nfs_direct_write_result().  Otherwise, if
+ * no requests have been sent, just return an error.
+ */
 static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
                                                struct iov_iter *iter,
-                                               loff_t pos, bool uio)
+                                               loff_t pos)
 {
         struct nfs_pageio_descriptor desc;
         struct inode *inode = dreq->inode;
         ssize_t result = 0;
         size_t requested_bytes = 0;
-        unsigned long seg;
+        size_t wsize = max_t(size_t, NFS_SERVER(inode)->wsize, PAGE_SIZE);
 
         NFS_PROTO(inode)->write_pageio_init(&desc, inode, FLUSH_COND_STABLE,
                               &nfs_direct_write_completion_ops);
@@ -875,16 +727,50 @@ static ssize_t nfs_direct_write_schedule_iovec(struct nfs_direct_req *dreq,
         get_dreq(dreq);
         atomic_inc(&inode->i_dio_count);
 
-        NFS_I(dreq->inode)->write_io += iov_iter_count(iter);
-        for (seg = 0; seg < iter->nr_segs; seg++) {
-                const struct iovec *vec = &iter->iov[seg];
-                result = nfs_direct_write_schedule_segment(&desc, vec, pos, uio);
+        NFS_I(inode)->write_io += iov_iter_count(iter);
+        while (iov_iter_count(iter)) {
+                struct page **pagevec;
+                size_t bytes;
+                size_t pgbase;
+                unsigned npages, i;
+
+                result = iov_iter_get_pages_alloc(iter, &pagevec, 
+                                                  wsize, &pgbase);
                 if (result < 0)
                         break;
-                requested_bytes += result;
-                if ((size_t)result < vec->iov_len)
+
+                bytes = result;
+                iov_iter_advance(iter, bytes);
+                npages = (result + pgbase + PAGE_SIZE - 1) / PAGE_SIZE;
+                for (i = 0; i < npages; i++) {
+                        struct nfs_page *req;
+                        unsigned int req_len = min_t(size_t, bytes, PAGE_SIZE - pgbase);
+
+                        req = nfs_create_request(dreq->ctx, inode,
+                                                 pagevec[i],
+                                                 pgbase, req_len);
+                        if (IS_ERR(req)) {
+                                result = PTR_ERR(req);
+                                break;
+                        }
+                        nfs_lock_request(req);
+                        req->wb_index = pos >> PAGE_SHIFT;
+                        req->wb_offset = pos & ~PAGE_MASK;
+                        if (!nfs_pageio_add_request(&desc, req)) {
+                                result = desc.pg_error;
+                                nfs_unlock_and_release_request(req);
+                                break;
+                        }
+                        pgbase = 0;
+                        bytes -= req_len;
+                        requested_bytes += req_len;
+                        pos += req_len;
+                        dreq->bytes_left -= req_len;
+                }
+                nfs_direct_release_pages(pagevec, npages);
+                kvfree(pagevec);
+                if (result < 0)
                         break;
-                pos += vec->iov_len;
         }
         nfs_pageio_complete(&desc);
 
@@ -985,7 +871,7 @@ ssize_t nfs_file_direct_write(struct kiocb *iocb, struct iov_iter *iter,
         if (!is_sync_kiocb(iocb))
                 dreq->iocb = iocb;
 
-        result = nfs_direct_write_schedule_iovec(dreq, iter, pos, uio);
+        result = nfs_direct_write_schedule_iovec(dreq, iter, pos);
 
         if (mapping->nrpages) {
                 invalidate_inode_pages2_range(mapping,