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dax, pmem: introduce an optional 'flush' dax_operation

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Filesystem-DAX flushes caches whenever it writes to the address returned
through dax_direct_access() and when writing back dirty radix entries.
That flushing is only required in the pmem case, so add a dax operation
to allow pmem to take this extra action, but skip it for other dax
capable devices that do not provide a flush routine.

An example for this differentiation might be a volatile ram disk where
there is no expectation of persistence. In fact the pmem driver itself might
front such an address range specified by the NFIT. So, this "no flush"
property might be something passed down by the bus / libnvdimm.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
This commit is contained in:
Dan Williams 2017-05-29 12:58:19 -07:00
parent fec53774fd
commit 3c1cebff23
2 changed files with 9 additions and 0 deletions
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7
drivers/nvdimm/pmem.c
View file

@ -242,9 +242,16 @@ static size_t pmem_copy_from_iter(struct dax_device *dax_dev, pgoff_t pgoff,
return copy_from_iter_flushcache(addr, bytes, i);
}
static void pmem_dax_flush(struct dax_device *dax_dev, pgoff_t pgoff,
void *addr, size_t size)
{
wb_cache_pmem(addr, size);
}
static const struct dax_operations pmem_dax_ops = {
.direct_access = pmem_dax_direct_access,
.copy_from_iter = pmem_copy_from_iter,
.flush = pmem_dax_flush,
};
static void pmem_release_queue(void *q)

2
include/linux/dax.h
View file

@ -19,6 +19,8 @@ struct dax_operations {
/* copy_from_iter: dax-driver override for default copy_from_iter */
size_t (*copy_from_iter)(struct dax_device *, pgoff_t, void *, size_t,
struct iov_iter *);
/* flush: optional driver-specific cache management after writes */
void (*flush)(struct dax_device *, pgoff_t, void *, size_t);
};
#if IS_ENABLED(CONFIG_DAX)