linux-ext4 - [PATCH] create_inode: fix copying large files

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Date:   Fri,  1 Feb 2019 12:51:59 +0000
From:   Ross Burton <ross.burton@...el.com>
To:     linux-ext4@...r.kernel.org
Subject: [PATCH] create_inode: fix copying large files

When copying large files into a ext filesystem at mkfs time the copy fails at
2^31 bytes in.  There are two problems:

copy_file_chunk() passes an offset (off_t, 64-bit typically) to
ext2fs_file_lseek() which expects a ext2_off_t (typedef to __u32) so the value
is truncated. Solve by calling ext2fs_file_llseek() which takes a u64 offset
instead.

try_lseek_copy() rounds the data and hole offsets as found by lseek() to block
boundaries, but the calculation gets truncated to 32-bits.  Solve by casting the
32-bit blocksize to off_t to ensure this doesn't happen.

Signed-off-by: Ross Burton <ross.burton@...el.com>
---
 misc/create_inode.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/misc/create_inode.c b/misc/create_inode.c
index 05aa6363..f106dcda 100644
--- a/misc/create_inode.c
+++ b/misc/create_inode.c
@@ -438,7 +438,7 @@ static errcode_t copy_file_chunk(ext2_filsys fs, int fd, ext2_file_t e2_file,
 				ptr += blen;
 				continue;
 			}
-			err = ext2fs_file_lseek(e2_file, off + bpos,
+			err = ext2fs_file_llseek(e2_file, off + bpos,
 						EXT2_SEEK_SET, NULL);
 			if (err)
 				goto fail;
@@ -481,7 +481,7 @@ static errcode_t try_lseek_copy(ext2_filsys fs, int fd, struct stat *statbuf,
 			return EXT2_ET_UNIMPLEMENTED;

 		data_blk = data & ~(fs->blocksize - 1);
-		hole_blk = (hole + (fs->blocksize - 1)) & ~(fs->blocksize - 1);
+		hole_blk = (hole + (off_t)(fs->blocksize - 1)) & ~(off_t)(fs->blocksize - 1);
 		err = copy_file_chunk(fs, fd, e2_file, data_blk, hole_blk, buf,
 				      zerobuf);
 		if (err)
-- 
2.11.0