linux-ext4 - [PATCH v2] mke2fs: fix coping of empty file using fiemap

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Date:   Tue, 17 Jan 2017 18:14:19 +0300
From:   Artem Blagodarenko <artem.blagodarenko@...gate.com>
To:     linux-ext4@...r.kernel.org
Subject: [PATCH v2] mke2fs: fix coping of empty file using fiemap

Hello,

Darrick J. Wong, thank you for inspection. Here is second version of the patch.

Changes since v1:
* errno is returned in case failed ioctl
* loop is terminated any time fm_mapped_extents == 0

During filesystem creation with -d option files copied from given
directory. If supported, FS_IOC_FIEMAP ioctl is used to get file
extents. For empty file fm_mapped_extents is 0 and no error code
is returned, because this is not fail situation.

Without this patch errno from previous operation is returned and
successful FS_IOC_FIEMAP ioctl call for empty file is interpreted
as error.

Signed-off-by: Artem Blagodarenko <artem.blagodarenko@...gate.com>
---
 misc/create_inode.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/misc/create_inode.c b/misc/create_inode.c
index 5122e56..d9e9b9b 100644
--- a/misc/create_inode.c
+++ b/misc/create_inode.c
@@ -510,10 +510,12 @@ static errcode_t try_fiemap_copy(ext2_filsys fs,
int fd, ext2_file_t e2_file,
         if (err < 0 && (errno == EOPNOTSUPP || errno == ENOTTY)) {
             err = EXT2_ET_UNIMPLEMENTED;
             goto out;
-        } else if (err < 0 || fiemap_buf->fm_mapped_extents == 0) {
+        } else if (err < 0) {
             err = errno;
             goto out;
-        }
+        } else if (fiemap_buf->fm_mapped_extents == 0)
+            goto out;
+
         for (i = 0, ext = ext_buf; i < fiemap_buf->fm_mapped_extents;
              i++, ext++) {
             err = copy_file_range(fs, fd, e2_file, ext->fe_logical,
--
--
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