Subject: Rework btrfs_file_write to only allocate while page locks are held

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

1 files changed, 133 insertions, 111 deletions

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index de8d47b44e12..6b455c2b3f03 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -207,6 +207,7 @@ int btrfs_drop_extents(struct btrfs_trans_handle *trans,
                         }
                         path->slots[0]--;
                 }
+next_slot:
                 keep = 0;
                 bookend = 0;
                 found_extent = 0;
@@ -214,39 +215,48 @@ int btrfs_drop_extents(struct btrfs_trans_handle *trans,
                 extent = NULL;
                 leaf = btrfs_buffer_leaf(path->nodes[0]);
                 slot = path->slots[0];
+                ret = 0;
                 btrfs_disk_key_to_cpu(&key, &leaf->items[slot].key);
                 if (key.offset >= end || key.objectid != inode->i_ino) {
-                        ret = 0;
                         goto out;
                 }
-                if (btrfs_key_type(&key) != BTRFS_EXTENT_DATA_KEY) {
-                        ret = 0;
+                if (btrfs_key_type(&key) > BTRFS_EXTENT_DATA_KEY) {
                         goto out;
                 }
-                extent = btrfs_item_ptr(leaf, slot,
-                                        struct btrfs_file_extent_item);
-                found_type = btrfs_file_extent_type(extent);
-                if (found_type == BTRFS_FILE_EXTENT_REG) {
-                        extent_end = key.offset +
-                                (btrfs_file_extent_num_blocks(extent) <<
-                                 inode->i_blkbits);
-                        found_extent = 1;
-                } else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
-                        found_inline = 1;
-                        extent_end = key.offset +
-                             btrfs_file_extent_inline_len(leaf->items + slot);
+                if (btrfs_key_type(&key) == BTRFS_EXTENT_DATA_KEY) {
+                        extent = btrfs_item_ptr(leaf, slot,
+                                                struct btrfs_file_extent_item);
+                        found_type = btrfs_file_extent_type(extent);
+                        if (found_type == BTRFS_FILE_EXTENT_REG) {
+                                extent_end = key.offset +
+                                        (btrfs_file_extent_num_blocks(extent) <<
+                                         inode->i_blkbits);
+                                found_extent = 1;
+                        } else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
+                                found_inline = 1;
+                                extent_end = key.offset +
+                                     btrfs_file_extent_inline_len(leaf->items +
+                                                                  slot);
+                        }
+                } else {
+                        extent_end = search_start;
                 }
 
                 /* we found nothing we can drop */
-                if (!found_extent && !found_inline) {
-                        ret = 0;
-                        goto out;
-                }
-
-                /* we found nothing inside the range */
-                if (search_start >= extent_end) {
-                        ret = 0;
-                        goto out;
+                if ((!found_extent && !found_inline) ||
+                    search_start >= extent_end) {
+                        int nextret;
+                        u32 nritems;
+                        nritems = btrfs_header_nritems(
+                                        btrfs_buffer_header(path->nodes[0]));
+                        if (slot >= nritems - 1) {
+                                nextret = btrfs_next_leaf(root, path);
+                                if (nextret)
+                                        goto out;
+                        } else {
+                                path->slots[0]++;
+                        }
+                        goto next_slot;
                 }
 
                 /* FIXME, there's only one inline extent allowed right now */
@@ -272,7 +282,6 @@ int btrfs_drop_extents(struct btrfs_trans_handle *trans,
                         WARN_ON(found_inline);
                         bookend = 1;
                 }
-
                 /* truncate existing extent */
                 if (start > key.offset) {
                         u64 new_num;
@@ -337,10 +346,14 @@ int btrfs_drop_extents(struct btrfs_trans_handle *trans,
                         ins.offset = end;
                         ins.flags = 0;
                         btrfs_set_key_type(&ins, BTRFS_EXTENT_DATA_KEY);
-
                         btrfs_release_path(root, path);
                         ret = btrfs_insert_empty_item(trans, root, path, &ins,
                                                       sizeof(*extent));
+
+                        if (ret) {
+                                btrfs_print_leaf(root, btrfs_buffer_leaf(path->nodes[0]));
+                                printk("got %d on inserting %Lu %u %Lu start %Lu end %Lu found %Lu %Lu\n", ret , ins.objectid, ins.flags, ins.offset, start, end, key.offset, extent_end);
+                        }
                         BUG_ON(ret);
                         extent = btrfs_item_ptr(
                                     btrfs_buffer_leaf(path->nodes[0]),
@@ -387,8 +400,7 @@ static int prepare_pages(struct btrfs_root *root,
                          loff_t pos,
                          unsigned long first_index,
                          unsigned long last_index,
-                         size_t write_bytes,
-                         u64 alloc_extent_start)
+                         size_t write_bytes)
 {
         int i;
         unsigned long index = pos >> PAGE_CACHE_SHIFT;
@@ -399,6 +411,16 @@ static int prepare_pages(struct btrfs_root *root,
         struct buffer_head *bh;
         struct buffer_head *head;
         loff_t isize = i_size_read(inode);
+        struct btrfs_trans_handle *trans;
+        u64 hint_block;
+        u64 num_blocks;
+        u64 alloc_extent_start;
+        u64 start_pos;
+        struct btrfs_key ins;
+
+        start_pos = pos & ~((u64)PAGE_CACHE_SIZE - 1);
+        num_blocks = (write_bytes + pos - start_pos + root->blocksize - 1) >>
+                        inode->i_blkbits;
 
         memset(pages, 0, num_pages * sizeof(struct page *));
 
@@ -408,6 +430,72 @@ static int prepare_pages(struct btrfs_root *root,
                         err = -ENOMEM;
                         goto failed_release;
                 }
+        }
+
+        mutex_lock(&root->fs_info->fs_mutex);
+        trans = btrfs_start_transaction(root, 1);
+        if (!trans) {
+                err = -ENOMEM;
+                mutex_unlock(&root->fs_info->fs_mutex);
+                goto out_unlock;
+        }
+        btrfs_set_trans_block_group(trans, inode);
+        /* FIXME blocksize != 4096 */
+        inode->i_blocks += num_blocks << 3;
+        hint_block = 0;
+
+        /* FIXME...EIEIO, ENOSPC and more */
+
+        /* step one, delete the existing extents in this range */
+        /* FIXME blocksize != pagesize */
+        if (start_pos < inode->i_size) {
+                err = btrfs_drop_extents(trans, root, inode,
+                         start_pos, (pos + write_bytes + root->blocksize -1) &
+                         ~((u64)root->blocksize - 1), &hint_block);
+                BUG_ON(err);
+        }
+
+        /* insert any holes we need to create */
+        if (inode->i_size < start_pos) {
+                u64 last_pos_in_file;
+                u64 hole_size;
+                u64 mask = root->blocksize - 1;
+                last_pos_in_file = (isize + mask) & ~mask;
+                hole_size = (start_pos - last_pos_in_file + mask) & ~mask;
+                hole_size >>= inode->i_blkbits;
+                if (last_pos_in_file < start_pos) {
+                        err = btrfs_insert_file_extent(trans, root,
+                                                       inode->i_ino,
+                                                       last_pos_in_file,
+                                                       0, 0, hole_size);
+                }
+                BUG_ON(err);
+        }
+
+        /*
+         * either allocate an extent for the new bytes or setup the key
+         * to show we are doing inline data in the extent
+         */
+        if (isize >= PAGE_CACHE_SIZE || pos + write_bytes < inode->i_size ||
+            pos + write_bytes - start_pos > BTRFS_MAX_INLINE_DATA_SIZE(root)) {
+                err = btrfs_alloc_extent(trans, root, inode->i_ino,
+                                         num_blocks, hint_block, (u64)-1,
+                                         &ins, 1);
+                BUG_ON(err);
+                err = btrfs_insert_file_extent(trans, root, inode->i_ino,
+                                       start_pos, ins.objectid, ins.offset,
+                                       ins.offset);
+                BUG_ON(err);
+        } else {
+                ins.offset = 0;
+                ins.objectid = 0;
+        }
+        BUG_ON(err);
+        alloc_extent_start = ins.objectid;
+        err = btrfs_end_transaction(trans, root);
+        mutex_unlock(&root->fs_info->fs_mutex);
+
+        for (i = 0; i < num_pages; i++) {
                 cancel_dirty_page(pages[i], PAGE_CACHE_SIZE);
                 wait_on_page_writeback(pages[i]);
                 offset = pos & (PAGE_CACHE_SIZE -1);
@@ -444,6 +532,11 @@ failed_truncate:
         if (pos > isize)
                 vmtruncate(inode, isize);
         return err;
+
+out_unlock:
+        mutex_unlock(&root->fs_info->fs_mutex);
+        goto failed_release;
+
 }
 
 static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
@@ -455,16 +548,14 @@ static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
         int ret = 0;
         struct inode *inode = file->f_path.dentry->d_inode;
         struct btrfs_root *root = BTRFS_I(inode)->root;
-        struct page *pages[8];
+        struct page **pages = NULL;
+        int nrptrs;
         struct page *pinned[2];
         unsigned long first_index;
         unsigned long last_index;
-        u64 start_pos;
-        u64 num_blocks;
-        u64 alloc_extent_start;
-        u64 hint_block;
-        struct btrfs_trans_handle *trans;
-        struct btrfs_key ins;
+
+        nrptrs = min((count + PAGE_CACHE_SIZE - 1) / PAGE_CACHE_SIZE,
+                     PAGE_CACHE_SIZE / (sizeof(struct page *)));
         pinned[0] = NULL;
         pinned[1] = NULL;
         if (file->f_flags & O_DIRECT)
@@ -482,9 +573,7 @@ static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
                 goto out;
         file_update_time(file);
 
-        start_pos = pos & ~((u64)PAGE_CACHE_SIZE - 1);
-        num_blocks = (count + pos - start_pos + root->blocksize - 1) >>
-                        inode->i_blkbits;
+        pages = kmalloc(nrptrs * sizeof(struct page *), GFP_KERNEL);
 
         mutex_lock(&inode->i_mutex);
         first_index = pos >> PAGE_CACHE_SHIFT;
@@ -516,87 +605,20 @@ static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
                 }
         }
 
-        mutex_lock(&root->fs_info->fs_mutex);
-        trans = btrfs_start_transaction(root, 1);
-        if (!trans) {
-                err = -ENOMEM;
-                mutex_unlock(&root->fs_info->fs_mutex);
-                goto out_unlock;
-        }
-        btrfs_set_trans_block_group(trans, inode);
-        /* FIXME blocksize != 4096 */
-        inode->i_blocks += num_blocks << 3;
-        hint_block = 0;
-
-        /* FIXME...EIEIO, ENOSPC and more */
-
-        /* step one, delete the existing extents in this range */
-        if (start_pos < inode->i_size) {
-                /* FIXME blocksize != pagesize */
-                ret = btrfs_drop_extents(trans, root, inode,
-                                         start_pos,
-                                         (pos + count + root->blocksize -1) &
-                                         ~((u64)root->blocksize - 1),
-                                         &hint_block);
-                BUG_ON(ret);
-        }
-
-        /* insert any holes we need to create */
-        if (inode->i_size < start_pos) {
-                u64 last_pos_in_file;
-                u64 hole_size;
-                u64 mask = root->blocksize - 1;
-                last_pos_in_file = (inode->i_size + mask) & ~mask;
-                hole_size = (start_pos - last_pos_in_file + mask) & ~mask;
-                hole_size >>= inode->i_blkbits;
-                if (last_pos_in_file < start_pos) {
-                        ret = btrfs_insert_file_extent(trans, root,
-                                                       inode->i_ino,
-                                                       last_pos_in_file,
-                                                       0, 0, hole_size);
-                }
-                BUG_ON(ret);
-        }
-
-        /*
-         * either allocate an extent for the new bytes or setup the key
-         * to show we are doing inline data in the extent
-         */
-        if (inode->i_size >= PAGE_CACHE_SIZE || pos + count < inode->i_size ||
-            pos + count - start_pos > BTRFS_MAX_INLINE_DATA_SIZE(root)) {
-                ret = btrfs_alloc_extent(trans, root, inode->i_ino,
-                                         num_blocks, hint_block, (u64)-1,
-                                         &ins, 1);
-                BUG_ON(ret);
-                ret = btrfs_insert_file_extent(trans, root, inode->i_ino,
-                                       start_pos, ins.objectid, ins.offset,
-                                       ins.offset);
-                BUG_ON(ret);
-        } else {
-                ins.offset = 0;
-                ins.objectid = 0;
-        }
-        BUG_ON(ret);
-        alloc_extent_start = ins.objectid;
-        ret = btrfs_end_transaction(trans, root);
-        mutex_unlock(&root->fs_info->fs_mutex);
-
         while(count > 0) {
                 size_t offset = pos & (PAGE_CACHE_SIZE - 1);
-                size_t write_bytes = min(count,
-                                         (size_t)PAGE_CACHE_SIZE - offset);
+                size_t write_bytes = min(count, nrptrs * PAGE_CACHE_SIZE -
+                                         offset);
                 size_t num_pages = (write_bytes + PAGE_CACHE_SIZE - 1) >>
                                         PAGE_CACHE_SHIFT;
 
+                WARN_ON(num_pages > nrptrs);
                 memset(pages, 0, sizeof(pages));
                 ret = prepare_pages(root, file, pages, num_pages,
                                     pos, first_index, last_index,
-                                    write_bytes, alloc_extent_start);
+                                    write_bytes);
                 BUG_ON(ret);
 
-                /* FIXME blocks != pagesize */
-                if (alloc_extent_start)
-                        alloc_extent_start += num_pages;
                 ret = btrfs_copy_from_user(pos, num_pages,
                                            write_bytes, pages, buf);
                 BUG_ON(ret);
@@ -611,13 +633,13 @@ static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
                 pos += write_bytes;
                 num_written += write_bytes;
 
-                balance_dirty_pages_ratelimited(inode->i_mapping);
+                balance_dirty_pages_ratelimited_nr(inode->i_mapping, num_pages);
                 btrfs_btree_balance_dirty(root);
                 cond_resched();
         }
-out_unlock:
         mutex_unlock(&inode->i_mutex);
 out:
+        kfree(pages);
         if (pinned[0])
                 page_cache_release(pinned[0]);
         if (pinned[1])