ext4: support simple conversion of extent-mapped inodes to use i_blocks
In order to make it simpler to test the code which support
i_blocks/indirect-mapped inodes, support the conversion of inodes
which are less than 12 blocks and which are contained in no more than
a single extent.
The primary intended use of this code is to converting freshly created
zero-length files and empty directories.
Note that the version of chattr in e2fsprogs 1.42.7 and earlier has a
check that prevents the clearing of the extent flag. A simple patch
which allows "chattr -e <file>" to work will be checked into the
e2fsprogs git repository.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index cbbe8a4..2352467 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -4610,3 +4610,62 @@
return error;
}
+
+/*
+ * Migrate a simple extent-based inode to use the i_blocks[] array
+ */
+int ext4_ind_migrate(struct inode *inode)
+{
+ struct ext4_extent_header *eh;
+ struct ext4_super_block *es = EXT4_SB(inode->i_sb)->s_es;
+ struct ext4_inode_info *ei = EXT4_I(inode);
+ struct ext4_extent *ex;
+ unsigned int i, len;
+ ext4_fsblk_t blk;
+ handle_t *handle;
+ int ret;
+
+ if (!EXT4_HAS_INCOMPAT_FEATURE(inode->i_sb,
+ EXT4_FEATURE_INCOMPAT_EXTENTS) ||
+ (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
+ return -EINVAL;
+
+ down_write(&EXT4_I(inode)->i_data_sem);
+ ret = ext4_ext_check_inode(inode);
+ if (ret)
+ goto errout;
+
+ eh = ext_inode_hdr(inode);
+ ex = EXT_FIRST_EXTENT(eh);
+ if (ext4_blocks_count(es) > EXT4_MAX_BLOCK_FILE_PHYS ||
+ eh->eh_depth != 0 || eh->eh_entries > 1) {
+ ret = -EOPNOTSUPP;
+ goto errout;
+ }
+ if (eh->eh_entries == 0)
+ blk = len = 0;
+ else {
+ len = le16_to_cpu(ex->ee_len);
+ blk = ext4_ext_pblock(ex);
+ if (len > EXT4_NDIR_BLOCKS) {
+ ret = -EOPNOTSUPP;
+ goto errout;
+ }
+ }
+
+ handle = ext4_journal_start(inode, EXT4_HT_MIGRATE, 1);
+ if (IS_ERR(handle)) {
+ ret = PTR_ERR(handle);
+ goto errout;
+ }
+
+ ext4_clear_inode_flag(inode, EXT4_INODE_EXTENTS);
+ memset(ei->i_data, 0, sizeof(ei->i_data));
+ for (i=0; i < len; i++)
+ ei->i_data[i] = cpu_to_le32(blk++);
+ ext4_mark_inode_dirty(handle, inode);
+ ext4_journal_stop(handle);
+errout:
+ up_write(&EXT4_I(inode)->i_data_sem);
+ return ret;
+}