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path: root/drivers/dax/device.c
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2018-01-23device-dax: Fix trailing semicolonLuis de Bethencourt
The trailing semicolon is an empty statement that does no operation. Removing it since it doesn't do anything. Signed-off-by: Luis de Bethencourt <luisbg@kernel.org> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2017-11-29device-dax: implement ->split() to catch invalid munmap attemptsDan Williams
Similar to how device-dax enforces that the 'address', 'offset', and 'len' parameters to mmap() be aligned to the device's fundamental alignment, the same constraints apply to munmap(). Implement ->split() to fail munmap calls that violate the alignment constraint. Otherwise, we later fail VM_BUG_ON checks in the unmap_page_range() path with crash signatures of the form: vma ffff8800b60c8a88 start 00007f88c0000000 end 00007f88c0e00000 next (null) prev (null) mm ffff8800b61150c0 prot 8000000000000027 anon_vma (null) vm_ops ffffffffa0091240 pgoff 0 file ffff8800b638ef80 private_data (null) flags: 0x380000fb(read|write|shared|mayread|maywrite|mayexec|mayshare|softdirty|mixedmap|hugepage) ------------[ cut here ]------------ kernel BUG at mm/huge_memory.c:2014! [..] RIP: 0010:__split_huge_pud+0x12a/0x180 [..] Call Trace: unmap_page_range+0x245/0xa40 ? __vma_adjust+0x301/0x990 unmap_vmas+0x4c/0xa0 unmap_region+0xae/0x120 ? __vma_rb_erase+0x11a/0x230 do_munmap+0x276/0x410 vm_munmap+0x6a/0xa0 SyS_munmap+0x1d/0x30 Link: http://lkml.kernel.org/r/151130418681.4029.7118245855057952010.stgit@dwillia2-desk3.amr.corp.intel.com Fixes: dee410792419 ("/dev/dax, core: file operations and dax-mmap") Signed-off-by: Dan Williams <dan.j.williams@intel.com> Reported-by: Jeff Moyer <jmoyer@redhat.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-10-19dev/dax: fix uninitialized variable build warningRoss Zwisler
Fix this build warning: warning: 'phys' may be used uninitialized in this function [-Wuninitialized] As reported here: https://lkml.org/lkml/2017/10/16/152 http://kisskb.ellerman.id.au/kisskb/buildresult/13181373/log/ Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2017-07-18device-dax: fix sysfs duplicate warningsDan Williams
Fix warnings of the form... WARNING: CPU: 10 PID: 4983 at fs/sysfs/dir.c:31 sysfs_warn_dup+0x62/0x80 sysfs: cannot create duplicate filename '/class/dax/dax12.0' Call Trace: dump_stack+0x63/0x86 __warn+0xcb/0xf0 warn_slowpath_fmt+0x5a/0x80 ? kernfs_path_from_node+0x4f/0x60 sysfs_warn_dup+0x62/0x80 sysfs_do_create_link_sd.isra.2+0x97/0xb0 sysfs_create_link+0x25/0x40 device_add+0x266/0x630 devm_create_dax_dev+0x2cf/0x340 [dax] dax_pmem_probe+0x1f5/0x26e [dax_pmem] nvdimm_bus_probe+0x71/0x120 ...by reusing the namespace id for the device-dax instance name. Now that we have decided that there will never by more than one device-dax instance per libnvdimm-namespace parent device [1], we can directly reuse the namepace ids. There are some possible follow-on cleanups, but those are saved for a later patch to simplify the -stable backport. [1]: https://lists.01.org/pipermail/linux-nvdimm/2016-December/008266.html Fixes: 98a29c39dc68 ("libnvdimm, namespace: allow creation of multiple pmem...") Cc: Jeff Moyer <jmoyer@redhat.com> Cc: <stable@vger.kernel.org> Reported-by: Dariusz Dokupil <dariusz.dokupil@intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2017-07-17device-dax: fix 'passing zero to ERR_PTR()' warningDan Williams
Dan Carpenter reports: The patch 7b6be8444e0f: "dax: refactor dax-fs into a generic provider of 'struct dax_device' instances" from Apr 11, 2017, leads to the following static checker warning: drivers/dax/device.c:643 devm_create_dev_dax() warn: passing zero to 'ERR_PTR' Fix the case where we inadvertently leak 0 to ERR_PTR() by setting at every error case, and make it clear that 'count' is never 0. Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2017-07-06fs: new infrastructure for writeback error handling and reportingJeff Layton
Most filesystems currently use mapping_set_error and filemap_check_errors for setting and reporting/clearing writeback errors at the mapping level. filemap_check_errors is indirectly called from most of the filemap_fdatawait_* functions and from filemap_write_and_wait*. These functions are called from all sorts of contexts to wait on writeback to finish -- e.g. mostly in fsync, but also in truncate calls, getattr, etc. The non-fsync callers are problematic. We should be reporting writeback errors during fsync, but many places spread over the tree clear out errors before they can be properly reported, or report errors at nonsensical times. If I get -EIO on a stat() call, there is no reason for me to assume that it is because some previous writeback failed. The fact that it also clears out the error such that a subsequent fsync returns 0 is a bug, and a nasty one since that's potentially silent data corruption. This patch adds a small bit of new infrastructure for setting and reporting errors during address_space writeback. While the above was my original impetus for adding this, I think it's also the case that current fsync semantics are just problematic for userland. Most applications that call fsync do so to ensure that the data they wrote has hit the backing store. In the case where there are multiple writers to the file at the same time, this is really hard to determine. The first one to call fsync will see any stored error, and the rest get back 0. The processes with open fds may not be associated with one another in any way. They could even be in different containers, so ensuring coordination between all fsync callers is not really an option. One way to remedy this would be to track what file descriptor was used to dirty the file, but that's rather cumbersome and would likely be slow. However, there is a simpler way to improve the semantics here without incurring too much overhead. This set adds an errseq_t to struct address_space, and a corresponding one is added to struct file. Writeback errors are recorded in the mapping's errseq_t, and the one in struct file is used as the "since" value. This changes the semantics of the Linux fsync implementation such that applications can now use it to determine whether there were any writeback errors since fsync(fd) was last called (or since the file was opened in the case of fsync having never been called). Note that those writeback errors may have occurred when writing data that was dirtied via an entirely different fd, but that's the case now with the current mapping_set_error/filemap_check_error infrastructure. This will at least prevent you from getting a false report of success. The new behavior is still consistent with the POSIX spec, and is more reliable for application developers. This patch just adds some basic infrastructure for doing this, and ensures that the f_wb_err "cursor" is properly set when a file is opened. Later patches will change the existing code to use this new infrastructure for reporting errors at fsync time. Signed-off-by: Jeff Layton <jlayton@redhat.com> Reviewed-by: Jan Kara <jack@suse.cz>
2017-05-04Merge branch 'for-4.12/dax' into libnvdimm-for-nextDan Williams
2017-04-19dax: introduce dax_operationsDan Williams
Track a set of dax_operations per dax_device that can be set at alloc_dax() time. These operations will be used to stop the abuse of block_device_operations for communicating dax capabilities to filesystems. It will also be used to replace the "pmem api" and move pmem-specific cache maintenance, and other dax-driver-specific filesystem-dax operations, to dax device methods. In particular this allows us to stop abusing __copy_user_nocache(), via memcpy_to_pmem(), with a driver specific replacement. This is a standalone introduction of the operations. Follow on patches convert each dax-driver and teach fs/dax.c to use ->direct_access() from dax_operations instead of block_device_operations. Suggested-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2017-04-19dax: add a facility to lookup a dax device by 'host' device nameDan Williams
For the current block_device based filesystem-dax path, we need a way for it to lookup the dax_device associated with a block_device. Add a 'host' property of a dax_device that can be used for this purpose. It is a free form string, but for a dax_device associated with a block device it is the bdev name. This is a stop-gap until filesystems are able to mount on a dax-inode directly. Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2017-04-12dax: refactor dax-fs into a generic provider of 'struct dax_device' instancesDan Williams
We want dax capable drivers to be able to publish a set of dax operations [1]. However, we do not want to further abuse block_devices to advertise these operations. Instead we will attach these operations to a dax device and add a lookup mechanism to go from block device path to a dax device. A dax capable driver like pmem or brd is responsible for registering a dax device, alongside a block device, and then a dax capable filesystem is responsible for retrieving the dax device by path name if it wants to call dax_operations. For now, we refactor the dax pseudo-fs to be a generic facility, rather than an implementation detail, of the device-dax use case. Where a "dax device" is just an inode + dax infrastructure, and "Device DAX" is a mapping service layered on top of that base 'struct dax_device'. "Filesystem DAX" is then a mapping service that layers a filesystem on top of that same base device. Filesystem DAX is associated with a block_device for now, but perhaps directly to a dax device in the future, or for new pmem-only filesystems. [1]: https://lkml.org/lkml/2017/1/19/880 Suggested-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Dan Williams <dan.j.williams@intel.com>