From: Adam Borowski <kilobyte@angband.pl>
To: linux-btrfs@vger.kernel.org, Goldwyn Rodrigues <rgoldwyn@suse.de>,
linux-fsdevel@vger.kernel.org, jack@suse.cz, david@fromorbit.com,
willy@infradead.org, hch@lst.de, darrick.wong@oracle.com,
dsterba@suse.cz, nborisov@suse.com, linux-nvdimm@lists.01.org
Cc: Adam Borowski <kilobyte@angband.pl>
Subject: [PATCH for-goldwyn] btrfs: disallow MAP_SYNC outside of DAX mounts
Date: Fri, 10 May 2019 17:32:22 +0200 [thread overview]
Message-ID: <20190510153222.24665-1-kilobyte@angband.pl> (raw)
In-Reply-To: <20190429172649.8288-13-rgoldwyn@suse.de>
Even if allocation is done synchronously, data would be lost except on
actual pmem. Explicit msync()s don't need MAP_SYNC, and don't require
a sync per page.
Signed-off-by: Adam Borowski <kilobyte@angband.pl>
---
MAP_SYNC can't be allowed unconditionally, as cacheline flushes don't help
guarantee persistency in page cache. This fixes an error in my earlier
patch "btrfs: allow MAP_SYNC mmap" -- you'd probably want to amend that.
fs/btrfs/file.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 362a9cf9dcb2..0bc5428037ba 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -2233,6 +2233,13 @@ static int btrfs_file_mmap(struct file *filp, struct vm_area_struct *vma)
if (!IS_DAX(inode) && !mapping->a_ops->readpage)
return -ENOEXEC;
+ /*
+ * Normal operation of btrfs is pretty much an antithesis of MAP_SYNC;
+ * supporting it outside DAX is pointless.
+ */
+ if (!IS_DAX(inode) && (vma->vm_flags & VM_SYNC))
+ return -EOPNOTSUPP;
+
file_accessed(filp);
if (IS_DAX(inode))
vma->vm_ops = &btrfs_dax_vm_ops;
--
2.20.1
next prev parent reply other threads:[~2019-05-10 15:33 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-29 17:26 [PATCH v4 00/18] btrfs dax support Goldwyn Rodrigues
2019-04-29 17:26 ` [PATCH 01/18] btrfs: create a mount option for dax Goldwyn Rodrigues
2019-05-21 18:02 ` Darrick J. Wong
2019-04-29 17:26 ` [PATCH 02/18] btrfs: Carve out btrfs_get_extent_map_write() out of btrfs_get_blocks_write() Goldwyn Rodrigues
2019-04-29 17:26 ` [PATCH 03/18] btrfs: basic dax read Goldwyn Rodrigues
2019-05-21 15:14 ` Darrick J. Wong
2019-05-22 21:50 ` Goldwyn Rodrigues
2019-04-29 17:26 ` [PATCH 04/18] dax: Introduce IOMAP_DAX_COW to CoW edges during writes Goldwyn Rodrigues
2019-05-21 16:51 ` Darrick J. Wong
2019-05-22 20:14 ` Goldwyn Rodrigues
2019-05-23 2:10 ` Dave Chinner
2019-05-23 9:05 ` Shiyang Ruan
2019-05-23 11:51 ` Goldwyn Rodrigues
2019-05-27 8:25 ` Shiyang Ruan
2019-05-28 9:17 ` Jan Kara
2019-05-29 2:01 ` Shiyang Ruan
2019-05-29 2:47 ` Dave Chinner
2019-05-29 4:02 ` Shiyang Ruan
2019-05-29 4:07 ` Darrick J. Wong
2019-05-29 4:46 ` Dave Chinner
2019-05-29 13:46 ` Jan Kara
2019-05-29 22:14 ` Dave Chinner
2019-05-30 11:16 ` Jan Kara
2019-05-30 22:59 ` Dave Chinner
2019-04-29 17:26 ` [PATCH 05/18] btrfs: return whether extent is nocow or not Goldwyn Rodrigues
2019-04-29 17:26 ` [PATCH 06/18] btrfs: Rename __endio_write_update_ordered() to btrfs_update_ordered_extent() Goldwyn Rodrigues
2019-04-29 17:26 ` [PATCH 07/18] btrfs: add dax write support Goldwyn Rodrigues
2019-05-21 17:08 ` Darrick J. Wong
2019-04-29 17:26 ` [PATCH 08/18] dax: memcpy page in case of IOMAP_DAX_COW for mmap faults Goldwyn Rodrigues
2019-05-21 17:46 ` Darrick J. Wong
2019-05-22 19:11 ` Goldwyn Rodrigues
2019-05-23 4:02 ` Darrick J. Wong
2019-05-23 12:10 ` Jan Kara
2019-04-29 17:26 ` [PATCH 09/18] btrfs: Add dax specific address_space_operations Goldwyn Rodrigues
2019-04-29 17:26 ` [PATCH 10/18] dax: replace mmap entry in case of CoW Goldwyn Rodrigues
2019-05-21 17:35 ` Darrick J. Wong
2019-05-23 13:38 ` Jan Kara
2019-04-29 17:26 ` [PATCH 11/18] btrfs: add dax mmap support Goldwyn Rodrigues
2019-04-29 17:26 ` [PATCH 12/18] btrfs: allow MAP_SYNC mmap Goldwyn Rodrigues
2019-05-10 15:32 ` Adam Borowski [this message]
2019-05-10 15:41 ` [PATCH for-goldwyn] btrfs: disallow MAP_SYNC outside of DAX mounts Dan Williams
2019-05-10 15:59 ` Pankaj Gupta
2019-05-23 13:44 ` [PATCH 12/18] btrfs: allow MAP_SYNC mmap Jan Kara
2019-05-23 16:19 ` Adam Borowski
2019-04-29 17:26 ` [PATCH 13/18] fs: dedup file range to use a compare function Goldwyn Rodrigues
2019-05-21 18:17 ` Darrick J. Wong
2019-04-29 17:26 ` [PATCH 14/18] dax: memcpy before zeroing range Goldwyn Rodrigues
2019-05-21 17:27 ` Darrick J. Wong
2019-04-29 17:26 ` [PATCH 15/18] btrfs: handle dax page zeroing Goldwyn Rodrigues
2019-04-29 17:26 ` [PATCH 16/18] btrfs: Writeprotect mmap pages on snapshot Goldwyn Rodrigues
2019-05-23 14:04 ` Jan Kara
2019-05-23 15:27 ` Goldwyn Rodrigues
2019-05-23 19:07 ` Jan Kara
2019-05-23 21:22 ` Goldwyn Rodrigues
2019-04-29 17:26 ` [PATCH 17/18] btrfs: Disable dax-based defrag and send Goldwyn Rodrigues
2019-04-29 17:26 ` [PATCH 18/18] btrfs: trace functions for btrfs_iomap_begin/end Goldwyn Rodrigues
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