Add an ioctl which forces all of the delay allocated blocks to be
allocated. This also provides a function ext4_alloc_da_blocks() which
will be used by the following commits to force files to be fully
allocated to preserve application-expected ext3 behaviour.
Signed-off-by: "Theodore Ts'o" <tytso@xxxxxxx>
---
fs/ext4/ext4.h | 2 ++
fs/ext4/inode.c | 42 ++++++++++++++++++++++++++++++++++++++++++
fs/ext4/ioctl.c | 13 +++++++++++++
3 files changed, 57 insertions(+), 0 deletions(-)
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 9840cad..626bda7 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -316,6 +316,7 @@ struct ext4_new_group_data {
#define EXT4_IOC_GROUP_EXTEND _IOW('f', 7, unsigned long)
#define EXT4_IOC_GROUP_ADD _IOW('f', 8, struct ext4_new_group_input)
#define EXT4_IOC_MIGRATE _IO('f', 9)
+#define EXT4_IOC_ALLOC_DA_BLKS _IO('f', 10)
/* note ioctl 11 reserved for filesystem-independent FIEMAP ioctl */
/*
@@ -1094,6 +1095,7 @@ extern int ext4_chunk_trans_blocks(struct inode *, int nrblocks);
extern int ext4_block_truncate_page(handle_t *handle,
struct address_space *mapping, loff_t from);
extern int ext4_page_mkwrite(struct vm_area_struct *vma, struct page *page);
+extern int ext4_alloc_da_blocks(struct inode *inode);
/* ioctl.c */
extern long ext4_ioctl(struct file *, unsigned int, unsigned long);
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 1216fb9..c66af1c 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -2807,6 +2807,48 @@ out:
return;
}
+/*
+ * Force all delayed allocation blocks to be allocated for a given inode.
+ */
+int ext4_alloc_da_blocks(struct inode *inode)
+{
+ if (!EXT4_I(inode)->i_reserved_data_blocks &&
+ !EXT4_I(inode)->i_reserved_meta_blocks)
+ return 0;
+
+ /*
+ * We do something simple for now. The filemap_flush() will
+ * also start triggering a write of the data blocks, which is
+ * not strictly speaking necessary (and for users of
+ * laptop_mode, not even desirable). However, to do otherwise
+ * would require replicating code paths in:
+ *
+ * ext4_da_writepages() ->
+ * write_cache_pages() ---> (via passed in callback function)
+ * __mpage_da_writepage() -->
+ * mpage_add_bh_to_extent()
+ * mpage_da_map_blocks()
+ *
+ * The problem is that write_cache_pages(), located in
+ * mm/page-writeback.c, marks pages clean in preparation for
+ * doing I/O, which is not desirable if we're not planning on
+ * doing I/O at all.
+ *
+ * We could call write_cache_pages(), and then redirty all of
+ * the pages by calling redirty_page_for_writeback() but that
+ * would be ugly in the extreme. So instead we would need to
+ * replicate parts of the code in the above functions,
+ * simplifying them becuase we wouldn't actually intend to
+ * write out the pages, but rather only collect contiguous
+ * logical block extents, call the multi-block allocator, and
+ * then update the buffer heads with the block allocations.
+ *
+ * For now, though, we'll cheat by calling filemap_flush(),
+ * which will map the blocks, and start the I/O, but not
+ * actually wait for the I/O to complete.
+ */
+ return filemap_flush(inode->i_mapping);
+}
/*
* bmap() is special. It gets used by applications such as lilo and by
diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index 22dd29f..0d59f5f 100644
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -262,6 +262,19 @@ setversion_out:
return err;
}
+ case EXT4_IOC_ALLOC_DA_BLKS:
+ {
+ int err;
+ if (!is_owner_or_cap(inode))
+ return -EACCES;
+
+ err = mnt_want_write(filp->f_path.mnt);
+ if (err)
+ return err;
+ err = ext4_alloc_da_blocks(inode);
+ return err;
+ }
+
default:
return -ENOTTY;
}
--
1.5.6.3
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