The patch titled
Subject: block: disable block device DAX by default
has been removed from the -mm tree. Its filename was
block-disable-block-device-dax-by-default.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Dan Williams <dan.j.williams@xxxxxxxxx>
Subject: block: disable block device DAX by default
The recent *sync enabling discovered that we are inserting into the
block_device pagecache counter to the expectations of the dirty data
tracking for dax mappings. This can lead to data corruption.
We want to support DAX for block devices eventually, but it requires wider
changes to properly manage the pagecache.
[<ffffffff81576d93>] dump_stack+0x85/0xc2
[<ffffffff812b9ee0>] dax_writeback_mapping_range+0x60/0xe0
[<ffffffff812a1d4f>] blkdev_writepages+0x3f/0x50
[<ffffffff811db011>] do_writepages+0x21/0x30
[<ffffffff811cb6a6>] __filemap_fdatawrite_range+0xc6/0x100
[<ffffffff811cb75a>] filemap_write_and_wait+0x4a/0xa0
[<ffffffff812a15e0>] set_blocksize+0x70/0xd0
[<ffffffff812a273d>] sb_set_blocksize+0x1d/0x50
[<ffffffff8132ac9b>] ext4_fill_super+0x75b/0x3360
[<ffffffff81583381>] ? vsnprintf+0x201/0x4c0
[<ffffffff815836d9>] ? snprintf+0x49/0x60
[<ffffffff81263010>] mount_bdev+0x180/0x1b0
[<ffffffff8132a540>] ? ext4_calculate_overhead+0x370/0x370
[<ffffffff8131ad95>] ext4_mount+0x15/0x20
[<ffffffff81263908>] mount_fs+0x38/0x170
Mark the support broken so its disabled by default, but otherwise still
available for testing.
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Signed-off-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
Reported-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
Suggested-by: Dave Chinner <david@xxxxxxxxxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxx>
Cc: Jens Axboe <axboe@xxxxxx>
Cc: Matthew Wilcox <matthew.r.wilcox@xxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxx>
Cc: Theodore Ts'o <tytso@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
block/Kconfig | 13 +++++++++++++
fs/block_dev.c | 6 +++++-
2 files changed, 18 insertions(+), 1 deletion(-)
diff -puN block/Kconfig~block-disable-block-device-dax-by-default block/Kconfig
--- a/block/Kconfig~block-disable-block-device-dax-by-default
+++ a/block/Kconfig
@@ -88,6 +88,19 @@ config BLK_DEV_INTEGRITY
T10/SCSI Data Integrity Field or the T13/ATA External Path
Protection. If in doubt, say N.
+config BLK_DEV_DAX
+ bool "Block device DAX support"
+ depends on FS_DAX
+ depends on BROKEN
+ help
+ When DAX support is available (CONFIG_FS_DAX) raw block
+ devices can also support direct userspace access to the
+ storage capacity via MMAP(2) similar to a file on a
+ DAX-enabled filesystem. However, the DAX I/O-path disables
+ some standard I/O-statistics, and the MMAP(2) path has some
+ operational differences due to bypassing the page
+ cache. If in doubt, say N.
+
config BLK_DEV_THROTTLING
bool "Block layer bio throttling support"
depends on BLK_CGROUP=y
diff -puN fs/block_dev.c~block-disable-block-device-dax-by-default fs/block_dev.c
--- a/fs/block_dev.c~block-disable-block-device-dax-by-default
+++ a/fs/block_dev.c
@@ -1201,7 +1201,11 @@ static int __blkdev_get(struct block_dev
bdev->bd_disk = disk;
bdev->bd_queue = disk->queue;
bdev->bd_contains = bdev;
- bdev->bd_inode->i_flags = disk->fops->direct_access ? S_DAX : 0;
+ if (IS_ENABLED(CONFIG_BLK_DEV_DAX) && disk->fops->direct_access)
+ bdev->bd_inode->i_flags = S_DAX;
+ else
+ bdev->bd_inode->i_flags = 0;
+
if (!partno) {
ret = -ENXIO;
bdev->bd_part = disk_get_part(disk, partno);
_
Patches currently in -mm which might be from dan.j.williams@xxxxxxxxx are
mm-config_nr_zones_extended.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
