ext4: fix punch hole on files with indirect mapping

Currently punch hole code on files with direct/indirect mapping has some
problems which may lead to a data loss. For example (from Jan Kara):

fallocate -n -p 10240000 4096

will punch the range 10240000 - 12632064 instead of the range 1024000 -
10244096.

Also the code is a bit weird and it's not using infrastructure provided
by indirect.c, but rather creating it's own way.

This patch fixes the issues as well as making the operation to run 4
times faster from my testing (punching out 60GB file). It uses similar
approach used in ext4_ind_truncate() which takes advantage of
ext4_free_branches() function.

Also rename the ext4_free_hole_blocks() to something more sensible, like
the equivalent we have for extent mapped files. Call it
ext4_ind_remove_space().

This has been tested mostly with fsx and some xfstests which are testing
punch hole but does not require unwritten extents which are not
supported with direct/indirect mapping. Not problems showed up even with
1024k block size.

CC: stable@vger.kernel.org
Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

1 files changed, 2 insertions, 2 deletions

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index d35c78c..5535ed2 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2143,8 +2143,8 @@ extern ssize_t ext4_ind_direct_IO(int rw, struct kiocb *iocb,
 extern int ext4_ind_calc_metadata_amount(struct inode *inode, sector_t lblock);
 extern int ext4_ind_trans_blocks(struct inode *inode, int nrblocks);
 extern void ext4_ind_truncate(handle_t *, struct inode *inode);
-extern int ext4_free_hole_blocks(handle_t *handle, struct inode *inode,
-				 ext4_lblk_t first, ext4_lblk_t stop);
+extern int ext4_ind_remove_space(handle_t *handle, struct inode *inode,
+				 ext4_lblk_t start, ext4_lblk_t end);
 
 /* ioctl.c */
 extern long ext4_ioctl(struct file *, unsigned int, unsigned long);