new helper: iov_iter_get_pages_alloc()
authorAl Viro <viro@zeniv.linux.org.uk>
Fri, 21 Mar 2014 08:58:33 +0000 (04:58 -0400)
committerAl Viro <viro@zeniv.linux.org.uk>
Tue, 6 May 2014 21:32:53 +0000 (17:32 -0400)
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>
drivers/staging/lustre/lustre/llite/rw26.c
fs/nfs/direct.c
include/linux/uio.h
mm/iov_iter.c

index f718585c9e08ea8542c41ec82d133aaa45aa7b36..6b5994577b6b9f61bbb704341c72f0fa088183b7 100644 (file)
@@ -218,14 +218,11 @@ static void ll_free_user_pages(struct page **pages, int npages, int do_dirty)
        int i;
 
        for (i = 0; i < npages; i++) {
-               if (pages[i] == NULL)
-                       break;
                if (do_dirty)
                        set_page_dirty_lock(pages[i]);
                page_cache_release(pages[i]);
        }
-
-       OBD_FREE_LARGE(pages, npages * sizeof(*pages));
+       kvfree(pages);
 }
 
 ssize_t ll_direct_rw_pages(const struct lu_env *env, struct cl_io *io,
@@ -370,10 +367,9 @@ static ssize_t ll_direct_IO_26(int rw, struct kiocb *iocb,
        struct file *file = iocb->ki_filp;
        struct inode *inode = file->f_mapping->host;
        struct ccc_object *obj = cl_inode2ccc(inode);
-       long count = iov_iter_count(iter);
-       long tot_bytes = 0, result = 0;
+       ssize_t count = iov_iter_count(iter);
+       ssize_t tot_bytes = 0, result = 0;
        struct ll_inode_info *lli = ll_i2info(inode);
-       unsigned long seg = 0;
        long size = MAX_DIO_SIZE;
        int refcheck;
 
@@ -407,63 +403,49 @@ static ssize_t ll_direct_IO_26(int rw, struct kiocb *iocb,
                mutex_lock(&inode->i_mutex);
 
        LASSERT(obj->cob_transient_pages == 0);
-       for (seg = 0; seg < iter->nr_segs; seg++) {
-               long iov_left = iter->iov[seg].iov_len;
-               unsigned long user_addr = (unsigned long)iter->iov[seg].iov_base;
+       while (iov_iter_count(iter)) {
+               struct page **pages;
+               size_t offs;
 
+               count = min_t(size_t, iov_iter_count(iter), size);
                if (rw == READ) {
                        if (file_offset >= i_size_read(inode))
                                break;
-                       if (file_offset + iov_left > i_size_read(inode))
-                               iov_left = i_size_read(inode) - file_offset;
+                       if (file_offset + count > i_size_read(inode))
+                               count = i_size_read(inode) - file_offset;
                }
 
-               while (iov_left > 0) {
-                       struct page **pages;
-                       int page_count, max_pages = 0;
-                       long bytes;
-
-                       bytes = min(size, iov_left);
-                       page_count = ll_get_user_pages(rw, user_addr, bytes,
-                                                      &pages, &max_pages);
-                       if (likely(page_count > 0)) {
-                               if (unlikely(page_count <  max_pages))
-                                       bytes = page_count << PAGE_CACHE_SHIFT;
-                               result = ll_direct_IO_26_seg(env, io, rw, inode,
-                                                            file->f_mapping,
-                                                            bytes, file_offset,
-                                                            pages, page_count);
-                               ll_free_user_pages(pages, max_pages, rw==READ);
-                       } else if (page_count == 0) {
-                               GOTO(out, result = -EFAULT);
-                       } else {
-                               result = page_count;
-                       }
-                       if (unlikely(result <= 0)) {
-                               /* If we can't allocate a large enough buffer
-                                * for the request, shrink it to a smaller
-                                * PAGE_SIZE multiple and try again.
-                                * We should always be able to kmalloc for a
-                                * page worth of page pointers = 4MB on i386. */
-                               if (result == -ENOMEM &&
-                                   size > (PAGE_CACHE_SIZE / sizeof(*pages)) *
-                                          PAGE_CACHE_SIZE) {
-                                       size = ((((size / 2) - 1) |
-                                                ~CFS_PAGE_MASK) + 1) &
-                                               CFS_PAGE_MASK;
-                                       CDEBUG(D_VFSTRACE,"DIO size now %lu\n",
-                                              size);
-                                       continue;
-                               }
-
-                               GOTO(out, result);
+               result = iov_iter_get_pages_alloc(iter, &pages, count, &offs);
+               if (likely(result > 0)) {
+                       int n = (result + offs + PAGE_SIZE - 1) / PAGE_SIZE;
+                       result = ll_direct_IO_26_seg(env, io, rw, inode,
+                                                    file->f_mapping,
+                                                    result, file_offset,
+                                                    pages, n);
+                       ll_free_user_pages(pages, n, rw==READ);
+               }
+               if (unlikely(result <= 0)) {
+                       /* If we can't allocate a large enough buffer
+                        * for the request, shrink it to a smaller
+                        * PAGE_SIZE multiple and try again.
+                        * We should always be able to kmalloc for a
+                        * page worth of page pointers = 4MB on i386. */
+                       if (result == -ENOMEM &&
+                           size > (PAGE_CACHE_SIZE / sizeof(*pages)) *
+                                  PAGE_CACHE_SIZE) {
+                               size = ((((size / 2) - 1) |
+                                        ~CFS_PAGE_MASK) + 1) &
+                                       CFS_PAGE_MASK;
+                               CDEBUG(D_VFSTRACE,"DIO size now %lu\n",
+                                      size);
+                               continue;
                        }
 
-                       tot_bytes += result;
-                       file_offset += result;
-                       iov_left -= result;
-                       user_addr += result;
+                       GOTO(out, result);
                }
+               iov_iter_advance(iter, result);
+               tot_bytes += result;
+               file_offset += result;
        }
 out:
        LASSERT(obj->cob_transient_pages == 0);
index 1d34f454989ea6a6310084d97f3835ea7e7066f2..b122fe21fea0dce3ae5dbcbb362dcbb4820e73b8 100644 (file)
@@ -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,
index 2f8825b066808d2741c03947c5db17eb3f9d4e09..4876e9f2a58f43b7178617d9b9c1a71d5ad75986 100644 (file)
@@ -73,6 +73,8 @@ void iov_iter_init(struct iov_iter *i, int direction, const struct iovec *iov,
                        unsigned long nr_segs, size_t count);
 ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages,
                        size_t maxsize, size_t *start);
+ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, struct page ***pages,
+                       size_t maxsize, size_t *start);
 int iov_iter_npages(const struct iov_iter *i, int maxpages);
 
 static inline size_t iov_iter_count(struct iov_iter *i)
index 0b677f8f9bad8576ad154c2707677fa32cd980d7..a5c691c1a283c62466ad4596d27035329a0d7949 100644 (file)
@@ -1,6 +1,8 @@
 #include <linux/export.h>
 #include <linux/uio.h>
 #include <linux/pagemap.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
 
 size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
                         struct iov_iter *i)
@@ -263,6 +265,44 @@ ssize_t iov_iter_get_pages(struct iov_iter *i,
 }
 EXPORT_SYMBOL(iov_iter_get_pages);
 
+ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
+                  struct page ***pages, size_t maxsize,
+                  size_t *start)
+{
+       size_t offset = i->iov_offset;
+       const struct iovec *iov = i->iov;
+       size_t len;
+       unsigned long addr;
+       void *p;
+       int n;
+       int res;
+
+       len = iov->iov_len - offset;
+       if (len > i->count)
+               len = i->count;
+       if (len > maxsize)
+               len = maxsize;
+       addr = (unsigned long)iov->iov_base + offset;
+       len += *start = addr & (PAGE_SIZE - 1);
+       addr &= ~(PAGE_SIZE - 1);
+       n = (len + PAGE_SIZE - 1) / PAGE_SIZE;
+       
+       p = kmalloc(n * sizeof(struct page *), GFP_KERNEL);
+       if (!p)
+               p = vmalloc(n * sizeof(struct page *));
+       if (!p)
+               return -ENOMEM;
+
+       res = get_user_pages_fast(addr, n, (i->type & WRITE) != WRITE, p);
+       if (unlikely(res < 0)) {
+               kvfree(p);
+               return res;
+       }
+       *pages = p;
+       return (res == n ? len : res * PAGE_SIZE) - *start;
+}
+EXPORT_SYMBOL(iov_iter_get_pages_alloc);
+
 int iov_iter_npages(const struct iov_iter *i, int maxpages)
 {
        size_t offset = i->iov_offset;