Re: [Libguestfs] mkfs.ext2 succeeds despite nbd write errors?

On Sat, Nov 7, 2015 at 3:02 PM, Richard W.M. Jones <rjones(a)redhat.com&gt; wrote: I locally patched mke2fs to check the return value of those two fsync() calls, and now it exits failure like it should: root@debian:~/mkfs/e2fsprogs-1.42.12/build/misc# strace ./mke2fs /dev/nbd0 2>&1 | tail write(1, "\10\10\10\10\1) = 5 pwrite(3, "\1\2\0\0\2\2\0\0\3\2\0\0\367{\365\37\2\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 4096, 6576672768) = 4096 fsync(3) = -1 EIO (Input/output error) pwrite(3, "\0\0\10\0\0\0 \0\231\231\1\0qm\37\0\365\377\7\0\0\0\0\0\2\0\0\0\2\0\0\0"..., 1024, 1024) = 1024 fsync(3) = -1 EIO (Input/output error) close(3) = 0 write(2, "\nWarning, had trouble writing ou"..., 46 Warning, had trouble writing out superblocks.) = 46 exit_group(5) = ? +++ exited with 5 +++ The patches are pretty simple: root@debian:~/mkfs# diff -urN e2fsprogs-1.42.12.orig/misc/filefrag.c e2fsprogs-1.42.12/misc/filefrag.c --- e2fsprogs-1.42.12.orig/misc/filefrag.c 2014-08-13 14:57:29.000000000 -0500 +++ e2fsprogs-1.42.12/misc/filefrag.c 2015-11-07 13:44:17.089128243 -0600 @@ -292,8 +292,11 @@ fm_ext.fe_flags = FIEMAP_EXTENT_MERGED; } - if (sync_file) - fsync(fd); + if (sync_file) { + int rc = fsync(fd); + if (rc < 0) + return rc; + } for (i = 0, logical = 0, *num_extents = 0, count = last_block = 0; i < numblocks; root@debian:~/mkfs# diff -urN e2fsprogs-1.42.12.orig/lib/ext2fs/unix_io.c e2fsprogs-1.42.12/lib/ext2fs/unix_io.c --- e2fsprogs-1.42.12.orig/lib/ext2fs/unix_io.c 2014-08-08 15:59:39.000000000 -0500 +++ e2fsprogs-1.42.12/lib/ext2fs/unix_io.c 2015-11-07 14:31:28.209005806 -0600 @@ -887,7 +887,9 @@ #ifndef NO_IO_CACHE retval = flush_cached_blocks(channel, data, 0); #endif - fsync(data->dev); + if (fsync(data->dev) == -1) + return errno; + return retval; } (attached) -jason