From: Theodore Ts'o <tytso@mit.edu>
Date: Tue, 13 Sep 2016 22:39:22 +0000 (-0400)
Subject: libext2fs: force DIO alignment FreeBSD when operating on a block device
X-Git-Tag: 1.43.4~39
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3a68c6f1f071c2826e8ec6ceb810c98719a98717;p=thirdparty%2Fe2fsprogs.git

libext2fs: force DIO alignment FreeBSD when operating on a block device

FreeBSD (and possibly BSD systems) requires that reads and writes to
block devices must be aligned, even when the O_DIRECT flag is not
specified.  Previously this was hard-coded to 512 bytes, but in order
to properly handle Advanced Format HDD's, query the BSD kernel to
determine the proper alignment to use.

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

diff --git a/lib/ext2fs/unix_io.c b/lib/ext2fs/unix_io.c
index 27b6a9560..85ad4e39f 100644
--- a/lib/ext2fs/unix_io.c
+++ b/lib/ext2fs/unix_io.c
@@ -613,7 +613,7 @@ static errcode_t unix_open_channel(const char *name, int fd,
 	}
 #endif
 
-#if defined(__CYGWIN__) || defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
+#if defined(__CYGWIN__)
 	/*
 	 * Some operating systems require that the buffers be aligned,
 	 * regardless of O_DIRECT
@@ -622,6 +622,14 @@ static errcode_t unix_open_channel(const char *name, int fd,
 		io->align = 512;
 #endif
 
+#if defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
+	if (io->flags & CHANNEL_FLAGS_BLOCK_DEVICE) {
+		int dio_align = ext2fs_get_dio_alignment(fd);
+
+		if (io->align < dio_align)
+			io->align = dio_align;
+	}
+#endif
 
 	if ((retval = alloc_cache(io, data)))
 		goto cleanup;