Btrfs: update hole handling v2

This patch splits the hole insertion code out of btrfs_setattr
into btrfs_cont_expand and updates btrfs_get_extent to properly
handle the case that file extent items are not continuous.

Signed-off-by: Yan Zheng <zheng.yan@oracle.com>

1 files changed, 100 insertions, 89 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index dd9cd01042b8..8254d6fa6910 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -2296,81 +2296,91 @@ out:
         return ret;
 }
 
-static int btrfs_setattr(struct dentry *dentry, struct iattr *attr)
+int btrfs_cont_expand(struct inode *inode, loff_t size)
 {
-        struct inode *inode = dentry->d_inode;
+        struct btrfs_trans_handle *trans;
+        struct btrfs_root *root = BTRFS_I(inode)->root;
+        struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
+        struct extent_map *em;
+        u64 mask = root->sectorsize - 1;
+        u64 hole_start = (inode->i_size + mask) & ~mask;
+        u64 block_end = (size + mask) & ~mask;
+        u64 last_byte;
+        u64 cur_offset;
+        u64 hole_size;
         int err;
 
-        err = inode_change_ok(inode, attr);
+        if (size <= hole_start)
+                return 0;
+
+        err = btrfs_check_free_space(root, 1, 0);
         if (err)
                 return err;
 
-        if (S_ISREG(inode->i_mode) &&
-            attr->ia_valid & ATTR_SIZE && attr->ia_size > inode->i_size) {
-                struct btrfs_trans_handle *trans;
-                struct btrfs_root *root = BTRFS_I(inode)->root;
-                struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
+        btrfs_truncate_page(inode->i_mapping, inode->i_size);
 
-                u64 mask = root->sectorsize - 1;
-                u64 hole_start = (inode->i_size + mask) & ~mask;
-                u64 block_end = (attr->ia_size + mask) & ~mask;
-                u64 hole_size;
-                u64 alloc_hint = 0;
+        while (1) {
+                struct btrfs_ordered_extent *ordered;
+                btrfs_wait_ordered_range(inode, hole_start,
+                                         block_end - hole_start);
+                lock_extent(io_tree, hole_start, block_end - 1, GFP_NOFS);
+                ordered = btrfs_lookup_ordered_extent(inode, hole_start);
+                if (!ordered)
+                        break;
+                unlock_extent(io_tree, hole_start, block_end - 1, GFP_NOFS);
+                btrfs_put_ordered_extent(ordered);
+        }
 
-                if (attr->ia_size <= hole_start)
-                        goto out;
+        trans = btrfs_start_transaction(root, 1);
+        btrfs_set_trans_block_group(trans, inode);
 
-                err = btrfs_check_free_space(root, 1, 0);
-                if (err)
-                        goto fail;
+        cur_offset = hole_start;
+        while (1) {
+                em = btrfs_get_extent(inode, NULL, 0, cur_offset,
+                                block_end - cur_offset, 0);
+                BUG_ON(IS_ERR(em) || !em);
+                last_byte = min(extent_map_end(em), block_end);
+                last_byte = (last_byte + mask) & ~mask;
+                if (test_bit(EXTENT_FLAG_VACANCY, &em->flags)) {
+                        hole_size = last_byte - cur_offset;
+                        err = btrfs_insert_file_extent(trans, root,
+                                        inode->i_ino, cur_offset, 0,
+                                        0, hole_size, 0, hole_size,
+                                        0, 0, 0);
+                        btrfs_drop_extent_cache(inode, hole_start,
+                                        last_byte - 1, 0);
+                }
+                free_extent_map(em);
+                cur_offset = last_byte;
+                if (err || cur_offset >= block_end)
+                        break;
+        }
 
-                btrfs_truncate_page(inode->i_mapping, inode->i_size);
+        btrfs_end_transaction(trans, root);
+        unlock_extent(io_tree, hole_start, block_end - 1, GFP_NOFS);
+        return err;
+}
 
-                hole_size = block_end - hole_start;
-                while(1) {
-                        struct btrfs_ordered_extent *ordered;
-                        btrfs_wait_ordered_range(inode, hole_start, hole_size);
-
-                        lock_extent(io_tree, hole_start, block_end - 1, GFP_NOFS);
-                        ordered = btrfs_lookup_ordered_extent(inode, hole_start);
-                        if (ordered) {
-                                unlock_extent(io_tree, hole_start,
-                                              block_end - 1, GFP_NOFS);
-                                btrfs_put_ordered_extent(ordered);
-                        } else {
-                                break;
-                        }
-                }
+static int btrfs_setattr(struct dentry *dentry, struct iattr *attr)
+{
+        struct inode *inode = dentry->d_inode;
+        int err;
 
-                trans = btrfs_start_transaction(root, 1);
-                btrfs_set_trans_block_group(trans, inode);
-                mutex_lock(&BTRFS_I(inode)->extent_mutex);
-                err = btrfs_drop_extents(trans, root, inode,
-                                         hole_start, block_end, hole_start,
-                                         &alloc_hint);
+        err = inode_change_ok(inode, attr);
+        if (err)
+                return err;
 
-                if (alloc_hint != EXTENT_MAP_INLINE) {
-                        err = btrfs_insert_file_extent(trans, root,
-                                                       inode->i_ino,
-                                                       hole_start, 0, 0,
-                                                       hole_size, 0, hole_size,
-                                                       0, 0, 0);
-                        btrfs_drop_extent_cache(inode, hole_start,
-                                                (u64)-1, 0);
-                        btrfs_check_file(root, inode);
-                }
-                mutex_unlock(&BTRFS_I(inode)->extent_mutex);
-                btrfs_end_transaction(trans, root);
-                unlock_extent(io_tree, hole_start, block_end - 1, GFP_NOFS);
+        if (S_ISREG(inode->i_mode) &&
+            attr->ia_valid & ATTR_SIZE && attr->ia_size > inode->i_size) {
+                err = btrfs_cont_expand(inode, attr->ia_size);
                 if (err)
                         return err;
         }
-out:
+
         err = inode_setattr(inode, attr);
 
         if (!err && ((attr->ia_valid & ATTR_MODE)))
                 err = btrfs_acl_chmod(inode);
-fail:
         return err;
 }
 
@@ -3456,27 +3466,44 @@ again:
         if (found_type == BTRFS_FILE_EXTENT_REG) {
                 extent_end = extent_start +
                        btrfs_file_extent_num_bytes(leaf, item);
-                err = 0;
-                if (start < extent_start || start >= extent_end) {
-                        em->start = start;
-                        if (start < extent_start) {
-                                if (start + len <= extent_start)
-                                        goto not_found;
-                                em->len = extent_end - extent_start;
-                        } else {
-                                em->len = len;
+        } else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
+                size_t size;
+                size = btrfs_file_extent_inline_len(leaf, item);
+                extent_end = (extent_start + size + root->sectorsize - 1) &
+                        ~((u64)root->sectorsize - 1);
+        }
+
+        if (start >= extent_end) {
+                path->slots[0]++;
+                if (path->slots[0] >= btrfs_header_nritems(leaf)) {
+                        ret = btrfs_next_leaf(root, path);
+                        if (ret < 0) {
+                                err = ret;
+                                goto out;
                         }
-                        goto not_found_em;
+                        if (ret > 0)
+                                goto not_found;
+                        leaf = path->nodes[0];
                 }
+                btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
+                if (found_key.objectid != objectid ||
+                    found_key.type != BTRFS_EXTENT_DATA_KEY)
+                        goto not_found;
+                if (start + len <= found_key.offset)
+                        goto not_found;
+                em->start = start;
+                em->len = found_key.offset - start;
+                goto not_found_em;
+        }
+
+        if (found_type == BTRFS_FILE_EXTENT_REG) {
+                em->start = extent_start;
+                em->len = extent_end - extent_start;
                 bytenr = btrfs_file_extent_disk_bytenr(leaf, item);
                 if (bytenr == 0) {
-                        em->start = extent_start;
-                        em->len = extent_end - extent_start;
                         em->block_start = EXTENT_MAP_HOLE;
                         goto insert;
                 }
-                em->start = extent_start;
-                em->len = extent_end - extent_start;
                 if (compressed) {
                         set_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
                         em->block_start = bytenr;
@@ -3489,38 +3516,21 @@ again:
                 }
                 goto insert;
         } else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
-                u64 page_start;
                 unsigned long ptr;
                 char *map;
                 size_t size;
                 size_t extent_offset;
                 size_t copy_size;
 
-                size = btrfs_file_extent_inline_len(leaf, item);
-                extent_end = (extent_start + size + root->sectorsize - 1) &
-                        ~((u64)root->sectorsize - 1);
-                if (start < extent_start || start >= extent_end) {
-                        em->start = start;
-                        if (start < extent_start) {
-                                if (start + len <= extent_start)
-                                        goto not_found;
-                                em->len = extent_end - extent_start;
-                        } else {
-                                em->len = len;
-                        }
-                        goto not_found_em;
-                }
                 em->block_start = EXTENT_MAP_INLINE;
-
                 if (!page || create) {
                         em->start = extent_start;
-                        em->len = (size + root->sectorsize - 1) &
-                        ~((u64)root->sectorsize - 1);
+                        em->len = extent_end - extent_start;
                         goto out;
                 }
 
-                page_start = page_offset(page) + pg_offset;
-                extent_offset = page_start - extent_start;
+                size = btrfs_file_extent_inline_len(leaf, item);
+                extent_offset = page_offset(page) + pg_offset - extent_start;
                 copy_size = min_t(u64, PAGE_CACHE_SIZE - pg_offset,
                                 size - extent_offset);
                 em->start = extent_start + extent_offset;
@@ -3570,6 +3580,7 @@ not_found:
         em->len = len;
 not_found_em:
         em->block_start = EXTENT_MAP_HOLE;
+        set_bit(EXTENT_FLAG_VACANCY, &em->flags);
 insert:
         btrfs_release_path(root, path);
         if (em->start > start || extent_map_end(em) <= start) {