Add kernel side support for BIO_DELETE/TRIM on UFS.

The FS_TRIM fs flag indicates that administrator requested issuing of
TRIM commands for the volume. UFS will only send the command to disk
if the disk reports GEOM::candelete attribute.

Since disk queue is reordered, data block is marked as free in the bitmap
only after TRIM command completed. Due to need to sleep waiting for
i/o to finish, TRIM bio_done routine schedules taskqueue to set the
bitmap bit.

Based on the patch by:	mckusick
Reviewed by:	mckusick, pjd
Tested by:	pho
MFC after:	1 month

1 files changed, 15 insertions, 0 deletions

diff --git a/sys/ufs/ffs/ffs_vfsops.c b/sys/ufs/ffs/ffs_vfsops.c
index 72f40da..f578382 100644
--- a/sys/ufs/ffs/ffs_vfsops.c
+++ b/sys/ufs/ffs/ffs_vfsops.c
@@ -895,6 +895,21 @@ ffs_mountfs(devvp, mp, td)
 		    mp->mnt_stat.f_mntonname);
 #endif
 	}
+	if ((fs->fs_flags & FS_TRIM) != 0) {
+		size = sizeof(int);
+		if (g_io_getattr("GEOM::candelete", cp, &size,
+		    &ump->um_candelete) == 0) {
+			if (!ump->um_candelete)
+				printf(
+"WARNING: %s: TRIM flag on fs but disk does not support TRIM\n",
+				    mp->mnt_stat.f_mntonname);
+		} else {
+			printf(
+"WARNING: %s: TRIM flag on fs but cannot get whether disk supports TRIM\n",
+			    mp->mnt_stat.f_mntonname);
+			ump->um_candelete = 0;
+		}
+	}
 
 	ump->um_mountp = mp;
 	ump->um_dev = dev;