ext4: fix EFBIG edge case when writing to large non-extent file
By running the following reproducer, we can confirm that the write
system call returns with 0 when it should return the error EFBIG.
#!/bin/sh
/bin/dd if=/dev/zero of=./img bs=1k count=1 seek=1024k > /dev/null 2>&1
/sbin/mkfs.ext3 -Fq ./img
/bin/mount -o loop -t ext4 ./img /mnt
/bin/touch /mnt/file
strace /bin/dd if=/dev/zero of=/mnt/file conv=notrunc bs=1k count=1 seek=$((2194719883264/1024)) 2>&1 | /bin/egrep "write.* 1024\) = "
/bin/umount /mnt
exit
Signed-off-by: Toshiyuki Okajima <toshi.okajima@jp.fujitsu.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: Eric Sandeen <sandeen@redhat.com>
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index bd411c1..ee92b66 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -70,7 +70,8 @@
struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
size_t length = iov_length(iov, nr_segs);
- if (pos > sbi->s_bitmap_maxbytes)
+ if ((pos > sbi->s_bitmap_maxbytes ||
+ (pos == sbi->s_bitmap_maxbytes && length > 0)))
return -EFBIG;
if (pos + length > sbi->s_bitmap_maxbytes) {