Btrfs: early work to file_write in big extents

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 59 insertions, 16 deletions

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 8dcf600e39ef..ec689992fdf4 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -1027,8 +1027,10 @@ static int btrfs_get_block_lock(struct inode *inode, sector_t iblock,
         path = btrfs_alloc_path();
         BUG_ON(!path);
         btrfs_init_path(path);
-        if (create)
+        if (create) {
                 trans = btrfs_start_transaction(root, 1);
+                WARN_ON(1);
+        }
 
         ret = btrfs_lookup_file_extent(trans, root, path,
                                        inode->i_ino,
@@ -1055,9 +1057,8 @@ static int btrfs_get_block_lock(struct inode *inode, sector_t iblock,
         /* exact match found, use it, FIXME, deal with extents
          * other than the page size
          */
-        if (ret == 0) {
+        if (0 && ret == 0) {
                 err = 0;
-                BUG_ON(btrfs_file_extent_disk_num_blocks(item) != 1);
                 if (create &&
                     btrfs_file_extent_generation(item) != trans->transid) {
                         struct btrfs_key ins;
@@ -1072,7 +1073,6 @@ static int btrfs_get_block_lock(struct inode *inode, sector_t iblock,
                         blocknr = ins.objectid;
 
                 }
-                map_bh(result, inode->i_sb, blocknr);
                 btrfs_map_bh_to_logical(root, result, blocknr);
                 goto out;
         }
@@ -1231,6 +1231,7 @@ static int dirty_and_release_pages(struct btrfs_trans_handle *trans,
                                    struct file *file,
                                    struct page **pages,
                                    size_t num_pages,
+                                   u64 extent_offset,
                                    loff_t pos,
                                    size_t write_bytes)
 {
@@ -1250,6 +1251,7 @@ static int dirty_and_release_pages(struct btrfs_trans_handle *trans,
                 trans = btrfs_start_transaction(root, 1);
                 btrfs_csum_file_block(trans, root, inode->i_ino,
                                       pages[i]->index << PAGE_CACHE_SHIFT,
+                                      extent_offset,
                                       kmap(pages[i]), PAGE_CACHE_SIZE);
                 kunmap(pages[i]);
                 SetPageChecked(pages[i]);
@@ -1279,7 +1281,8 @@ static int prepare_pages(struct btrfs_trans_handle *trans,
                          loff_t pos,
                          unsigned long first_index,
                          unsigned long last_index,
-                         size_t write_bytes)
+                         size_t write_bytes,
+                         u64 alloc_extent_start)
 {
         int i;
         unsigned long index = pos >> PAGE_CACHE_SHIFT;
@@ -1288,6 +1291,8 @@ static int prepare_pages(struct btrfs_trans_handle *trans,
         int err = 0;
         int ret;
         int this_write;
+        struct buffer_head *bh;
+        struct buffer_head *head;
         loff_t isize = i_size_read(inode);
 
         memset(pages, 0, num_pages * sizeof(struct page *));
@@ -1307,14 +1312,20 @@ static int prepare_pages(struct btrfs_trans_handle *trans,
                         BUG_ON(ret);
                         lock_page(pages[i]);
                 }
-                ret = nobh_prepare_write(pages[i], offset,
-                                         offset + this_write,
-                                         btrfs_get_block);
+                create_empty_buffers(pages[i], root->fs_info->sb->s_blocksize,
+                                     (1 << BH_Uptodate));
+                head = page_buffers(pages[i]);
+                bh = head;
+                do {
+                        err = btrfs_map_bh_to_logical(root, bh,
+                                                      alloc_extent_start);
+                        BUG_ON(err);
+                        if (err)
+                                goto failed_truncate;
+                        bh = bh->b_this_page;
+                        alloc_extent_start++;
+                } while (bh != head);
                 pos += this_write;
-                if (ret) {
-                        err = ret;
-                        goto failed_truncate;
-                }
                 WARN_ON(this_write > write_bytes);
                 write_bytes -= this_write;
         }
@@ -1343,11 +1354,23 @@ static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
         struct page *pages[1];
         unsigned long first_index;
         unsigned long last_index;
+        u64 start_pos;
+        u64 num_blocks;
+        u64 alloc_extent_start;
+        u64 orig_extent_start;
+        struct btrfs_trans_handle *trans;
 
         if (file->f_flags & O_DIRECT)
                 return -EINVAL;
         pos = *ppos;
 
+        start_pos = pos & ~(root->blocksize - 1);
+        /* FIXME */
+        if (start_pos != pos)
+                return -EINVAL;
+        num_blocks = (count + pos - start_pos + root->blocksize - 1) >>
+                        inode->i_blkbits;
+
         vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
         current->backing_dev_info = inode->i_mapping->backing_dev_info;
         err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
@@ -1362,20 +1385,41 @@ static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
         mutex_lock(&inode->i_mutex);
         first_index = pos >> PAGE_CACHE_SHIFT;
         last_index = (pos + count) >> PAGE_CACHE_SHIFT;
+
+        mutex_lock(&root->fs_info->fs_mutex);
+        trans = btrfs_start_transaction(root, 1);
+        if (!trans) {
+                err = -ENOMEM;
+                goto out_unlock;
+        }
+        ret = btrfs_alloc_file_extent(trans, root, inode->i_ino,
+                                      start_pos, num_blocks, 1,
+                                      &alloc_extent_start);
+        BUG_ON(ret);
+
+        orig_extent_start = start_pos;
+        ret = btrfs_end_transaction(trans, root);
+        BUG_ON(ret);
+        mutex_unlock(&root->fs_info->fs_mutex);
+
         while(count > 0) {
                 size_t offset = pos & (PAGE_CACHE_SIZE - 1);
                 size_t write_bytes = min(count, PAGE_CACHE_SIZE - offset);
                 size_t num_pages = (write_bytes + PAGE_CACHE_SIZE - 1) >>
                                         PAGE_CACHE_SHIFT;
                 ret = prepare_pages(NULL, root, file, pages, num_pages,
-                                    pos, first_index, last_index, write_bytes);
+                                    pos, first_index, last_index,
+                                    write_bytes, alloc_extent_start);
                 BUG_ON(ret);
+                /* FIXME blocks != pagesize */
+                alloc_extent_start += num_pages;
                 ret = btrfs_copy_from_user(pos, num_pages,
                                            write_bytes, pages, buf);
                 BUG_ON(ret);
 
                 ret = dirty_and_release_pages(NULL, root, file, pages,
-                                              num_pages, pos, write_bytes);
+                                              num_pages, orig_extent_start,
+                                              pos, write_bytes);
                 BUG_ON(ret);
                 btrfs_drop_pages(pages, num_pages);
 
@@ -1387,6 +1431,7 @@ static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
                 balance_dirty_pages_ratelimited(inode->i_mapping);
                 cond_resched();
         }
+out_unlock:
         mutex_unlock(&inode->i_mutex);
 out:
         *ppos = pos;
@@ -1806,8 +1851,6 @@ static int create_snapshot(struct btrfs_root *root, char *name, int namelen)
                                 &new_root_item);
         BUG_ON(ret);
 
-printk("adding snapshot name %.*s root %Lu %Lu %u\n", namelen, name, key.objectid, key.offset, key.flags);
-
         /*
          * insert the directory item
          */