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block: revert runtime dax control of the raw block device

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Dynamically enabling DAX requires that the page cache first be flushed
and invalidated.  This must occur atomically with the change of DAX mode
otherwise we confuse the fsync/msync tracking and violate data
durability guarantees.  Eliminate the possibilty of DAX-disabled to
DAX-enabled transitions for now and revisit this for the next cycle.

Cc: Jan Kara <jack@suse.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Matthew Wilcox <willy@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
This commit is contained in:
Dan Williams 2016-01-28 20:13:39 -08:00
parent 65f87ee718
commit 9f4736fe7c
4 changed files with 0 additions and 70 deletions
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38
block/ioctl.c
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@ -434,42 +434,6 @@ bool blkdev_dax_capable(struct block_device *bdev)
return true;
}
static int blkdev_daxset(struct block_device *bdev, unsigned long argp)
{
unsigned long arg;
int rc = 0;
if (!capable(CAP_SYS_ADMIN))
return -EACCES;
if (get_user(arg, (int __user *)(argp)))
return -EFAULT;
arg = !!arg;
if (arg == !!(bdev->bd_inode->i_flags & S_DAX))
return 0;
if (arg)
arg = S_DAX;
if (arg && !blkdev_dax_capable(bdev))
return -ENOTTY;
inode_lock(bdev->bd_inode);
if (bdev->bd_map_count == 0)
inode_set_flags(bdev->bd_inode, arg, S_DAX);
else
rc = -EBUSY;
inode_unlock(bdev->bd_inode);
return rc;
}
#else
static int blkdev_daxset(struct block_device *bdev, int arg)
{
if (arg)
return -ENOTTY;
return 0;
}
#endif
static int blkdev_flushbuf(struct block_device *bdev, fmode_t mode,
@ -634,8 +598,6 @@ int blkdev_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd,
case BLKTRACESETUP:
case BLKTRACETEARDOWN:
return blk_trace_ioctl(bdev, cmd, argp);
case BLKDAXSET:
return blkdev_daxset(bdev, arg);
case BLKDAXGET:
return put_int(arg, !!(bdev->bd_inode->i_flags & S_DAX));
break;

28
fs/block_dev.c
View File

@ -1736,37 +1736,13 @@ static int blkdev_dax_pmd_fault(struct vm_area_struct *vma, unsigned long addr,
return __dax_pmd_fault(vma, addr, pmd, flags, blkdev_get_block, NULL);
}
static void blkdev_vm_open(struct vm_area_struct *vma)
{
struct inode *bd_inode = bdev_file_inode(vma->vm_file);
struct block_device *bdev = I_BDEV(bd_inode);
inode_lock(bd_inode);
bdev->bd_map_count++;
inode_unlock(bd_inode);
}
static void blkdev_vm_close(struct vm_area_struct *vma)
{
struct inode *bd_inode = bdev_file_inode(vma->vm_file);
struct block_device *bdev = I_BDEV(bd_inode);
inode_lock(bd_inode);
bdev->bd_map_count--;
inode_unlock(bd_inode);
}
static const struct vm_operations_struct blkdev_dax_vm_ops = {
.open = blkdev_vm_open,
.close = blkdev_vm_close,
.fault = blkdev_dax_fault,
.pmd_fault = blkdev_dax_pmd_fault,
.pfn_mkwrite = blkdev_dax_fault,
};
static const struct vm_operations_struct blkdev_default_vm_ops = {
.open = blkdev_vm_open,
.close = blkdev_vm_close,
.fault = filemap_fault,
.map_pages = filemap_map_pages,
};
@ -1774,18 +1750,14 @@ static const struct vm_operations_struct blkdev_default_vm_ops = {
static int blkdev_mmap(struct file *file, struct vm_area_struct *vma)
{
struct inode *bd_inode = bdev_file_inode(file);
struct block_device *bdev = I_BDEV(bd_inode);
file_accessed(file);
inode_lock(bd_inode);
bdev->bd_map_count++;
if (IS_DAX(bd_inode)) {
vma->vm_ops = &blkdev_dax_vm_ops;
vma->vm_flags |= VM_MIXEDMAP | VM_HUGEPAGE;
} else {
vma->vm_ops = &blkdev_default_vm_ops;
}
inode_unlock(bd_inode);
return 0;
}

3
include/linux/fs.h
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@ -484,9 +484,6 @@ struct block_device {
int bd_fsfreeze_count;
/* Mutex for freeze */
struct mutex bd_fsfreeze_mutex;
#ifdef CONFIG_FS_DAX
int bd_map_count;
#endif
};
/*

1
include/uapi/linux/fs.h
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@ -222,7 +222,6 @@ struct fsxattr {
#define BLKSECDISCARD _IO(0x12,125)
#define BLKROTATIONAL _IO(0x12,126)
#define BLKZEROOUT _IO(0x12,127)
#define BLKDAXSET _IO(0x12,128)
#define BLKDAXGET _IO(0x12,129)
#define BMAP_IOCTL 1 /* obsolete - kept for compatibility */