libext2fs: call fsync(2) to clear stale errors for a new a unix I/O channel

Newer versions of Linux will retain errors and allow them to be
returned by fsync() or close(), even if the error happened before the
file descriptor was opened.  This was to accomodate Postgres's
"interesting" method of error collection.

Unfortunately, for e2fsck, we never want to see stale errors, as this
can cause xfstests (such generic/347) to fail with a false positive.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/lib/ext2fs/unix_io.c b/lib/ext2fs/unix_io.c
index 53fbd28bf8032ea793f6e825d5e0d7ff1f15eea5..18a2e5f75c073c45a4af020c30b37c62ef73a1a0 100644 (file)
--- a/lib/ext2fs/unix_io.c
+++ b/lib/ext2fs/unix_io.c
@@ -569,6 +569,14 @@ static errcode_t unix_open_channel(const char *name, int fd,
        if (safe_getenv("UNIX_IO_FORCE_BOUNCE"))
                flags |= IO_FLAG_FORCE_BOUNCE;
 
+#ifdef __linux__
+       /*
+        * We need to make sure any previous errors in the block
+        * device are thrown away, sigh.
+        */
+       (void) fsync(fd);
+#endif
+
        retval = ext2fs_get_mem(sizeof(struct struct_io_channel), &io);
        if (retval)
                goto cleanup;