tmpfs: add support for read_iter and write_iter

Convert tmpfs do_shmem_file_read() to shmem_file_read_iter().
Make file_read_iter_actor() global so tmpfs can use it too: delete
file_read_actor(), which was made global in 2.4.4 for use by tmpfs.
Replace tmpfs generic_file_aio_write() by generic_file_write_iter().

Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 9e29beb60a13b612770649e2f18bafe362e08b84..6f1384c12a69dc2f5e457063115d2c54c7d6cfc4 100644 (file)
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2504,8 +2504,9 @@ extern int sb_min_blocksize(struct super_block *, int);
 extern int generic_file_mmap(struct file *, struct vm_area_struct *);
 extern int generic_file_readonly_mmap(struct file *, struct vm_area_struct *);
 extern int generic_file_remap_pages(struct vm_area_struct *, unsigned long addr,
-               unsigned long size, pgoff_t pgoff);
-extern int file_read_actor(read_descriptor_t * desc, struct page *page, unsigned long offset, unsigned long size);
+                               unsigned long size, pgoff_t pgoff);
+extern int file_read_iter_actor(read_descriptor_t *desc, struct page *page,
+                               unsigned long offset, unsigned long size);
 int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk);
 extern ssize_t generic_file_aio_read(struct kiocb *, const struct iovec *, unsigned long, loff_t);
 extern ssize_t generic_file_read_iter(struct kiocb *, struct iov_iter *,

diff --git a/mm/filemap.c b/mm/filemap.c
index 1ac1ceeb4d9a064464e3872f87cc2de786b537f1..9b0b85223d5c2b261399be95b9a38e0370bd4428 100644 (file)
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1315,44 +1315,6 @@ out:
        file_accessed(filp);
 }
 
-int file_read_actor(read_descriptor_t *desc, struct page *page,
-                       unsigned long offset, unsigned long size)
-{
-       char *kaddr;
-       unsigned long left, count = desc->count;
-
-       if (size > count)
-               size = count;
-
-       /*
-        * Faults on the destination of a read are common, so do it before
-        * taking the kmap.
-        */
-       if (!fault_in_pages_writeable(desc->arg.buf, size)) {
-               kaddr = kmap_atomic(page);
-               left = __copy_to_user_inatomic(desc->arg.buf,
-                                               kaddr + offset, size);
-               kunmap_atomic(kaddr);
-               if (left == 0)
-                       goto success;
-       }
-
-       /* Do it the slow way */
-       kaddr = kmap(page);
-       left = __copy_to_user(desc->arg.buf, kaddr + offset, size);
-       kunmap(page);
-
-       if (left) {
-               size -= left;
-               desc->error = -EFAULT;
-       }
-success:
-       desc->count = count - size;
-       desc->written += size;
-       desc->arg.buf += size;
-       return size;
-}
-
 /*
  * Performs necessary checks before doing a write
  * @iov:       io vector request
@@ -1392,8 +1354,8 @@ int generic_segment_checks(const struct iovec *iov,
 }
 EXPORT_SYMBOL(generic_segment_checks);
 
-static int file_read_iter_actor(read_descriptor_t *desc, struct page *page,
-                               unsigned long offset, unsigned long size)
+int file_read_iter_actor(read_descriptor_t *desc, struct page *page,
+                        unsigned long offset, unsigned long size)
 {
        struct iov_iter *iter = desc->arg.data;
        unsigned long copied = 0;

diff --git a/mm/shmem.c b/mm/shmem.c
index 8297623fcaedec21b37b5080d376967e673afe92..8612a95d7d7e2f7ddba00076b3db0e13b2f8c7c5 100644 (file)
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1464,14 +1464,23 @@ shmem_write_end(struct file *file, struct address_space *mapping,
        return copied;
 }
 
-static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor)
+static ssize_t shmem_file_read_iter(struct kiocb *iocb,
+                                   struct iov_iter *iter, loff_t pos)
 {
+       read_descriptor_t desc;
+       loff_t *ppos = &iocb->ki_pos;
+       struct file *filp = iocb->ki_filp;
        struct inode *inode = file_inode(filp);
        struct address_space *mapping = inode->i_mapping;
        pgoff_t index;
        unsigned long offset;
        enum sgp_type sgp = SGP_READ;
 
+       desc.written = 0;
+       desc.count = iov_iter_count(iter);
+       desc.arg.data = iter;
+       desc.error = 0;
+
        /*
         * Might this read be for a stacking filesystem?  Then when reading
         * holes of a sparse file, we actually need to allocate those pages,
@@ -1498,10 +1507,10 @@ static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_
                                break;
                }
 
-               desc->error = shmem_getpage(inode, index, &page, sgp, NULL);
-               if (desc->error) {
-                       if (desc->error == -EINVAL)
-                               desc->error = 0;
+               desc.error = shmem_getpage(inode, index, &page, sgp, NULL);
+               if (desc.error) {
+                       if (desc.error == -EINVAL)
+                               desc.error = 0;
                        break;
                }
                if (page)
@@ -1552,13 +1561,13 @@ static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_
                 * "pos" here (the actor routine has to update the user buffer
                 * pointers and the remaining count).
                 */
-               ret = actor(desc, page, offset, nr);
+               ret = file_read_iter_actor(&desc, page, offset, nr);
                offset += ret;
                index += offset >> PAGE_CACHE_SHIFT;
                offset &= ~PAGE_CACHE_MASK;
 
                page_cache_release(page);
-               if (ret != nr || !desc->count)
+               if (ret != nr || !desc.count)
                        break;
 
                cond_resched();
@@ -1566,40 +1575,8 @@ static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_
 
        *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
        file_accessed(filp);
-}
-
-static ssize_t shmem_file_aio_read(struct kiocb *iocb,
-               const struct iovec *iov, unsigned long nr_segs, loff_t pos)
-{
-       struct file *filp = iocb->ki_filp;
-       ssize_t retval;
-       unsigned long seg;
-       size_t count;
-       loff_t *ppos = &iocb->ki_pos;
 
-       retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE);
-       if (retval)
-               return retval;
-
-       for (seg = 0; seg < nr_segs; seg++) {
-               read_descriptor_t desc;
-
-               desc.written = 0;
-               desc.arg.buf = iov[seg].iov_base;
-               desc.count = iov[seg].iov_len;
-               if (desc.count == 0)
-                       continue;
-               desc.error = 0;
-               do_shmem_file_read(filp, ppos, &desc, file_read_actor);
-               retval += desc.written;
-               if (desc.error) {
-                       retval = retval ?: desc.error;
-                       break;
-               }
-               if (desc.count > 0)
-                       break;
-       }
-       return retval;
+       return desc.written ? desc.written : desc.error;
 }
 
 static ssize_t shmem_file_splice_read(struct file *in, loff_t *ppos,
@@ -2724,8 +2701,8 @@ static const struct file_operations shmem_file_operations = {
        .llseek         = shmem_file_llseek,
        .read           = do_sync_read,
        .write          = do_sync_write,
-       .aio_read       = shmem_file_aio_read,
-       .aio_write      = generic_file_aio_write,
+       .read_iter      = shmem_file_read_iter,
+       .write_iter     = generic_file_write_iter,
        .fsync          = noop_fsync,
        .splice_read    = shmem_file_splice_read,
        .splice_write   = generic_file_splice_write,