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fsdax: unshare: zero destination if srcmap is HOLE or UNWRITTEN
commit13dd4e0462
upstream. unshare copies data from source to destination. But if the source is HOLE or UNWRITTEN extents, we should zero the destination, otherwise the HOLE or UNWRITTEN part will be user-visible old data of the new allocated extent. Found by running generic/649 while mounting with -o dax=always on pmem. Link: https://lkml.kernel.org/r/1679483469-2-1-git-send-email-ruansy.fnst@fujitsu.com Fixes:d984648e42
("fsdax,xfs: port unshare to fsdax") Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Darrick J. Wong <djwong@kernel.org> Cc: Jan Kara <jack@suse.cz> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Alistair Popple <apopple@nvidia.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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1 changed files with 8 additions and 3 deletions
11
fs/dax.c
11
fs/dax.c
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@ -1258,15 +1258,20 @@ static s64 dax_unshare_iter(struct iomap_iter *iter)
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/* don't bother with blocks that are not shared to start with */
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if (!(iomap->flags & IOMAP_F_SHARED))
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return length;
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/* don't bother with holes or unwritten extents */
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if (srcmap->type == IOMAP_HOLE || srcmap->type == IOMAP_UNWRITTEN)
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return length;
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id = dax_read_lock();
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ret = dax_iomap_direct_access(iomap, pos, length, &daddr, NULL);
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if (ret < 0)
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goto out_unlock;
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/* zero the distance if srcmap is HOLE or UNWRITTEN */
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if (srcmap->flags & IOMAP_F_SHARED || srcmap->type == IOMAP_UNWRITTEN) {
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memset(daddr, 0, length);
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dax_flush(iomap->dax_dev, daddr, length);
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ret = length;
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goto out_unlock;
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}
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ret = dax_iomap_direct_access(srcmap, pos, length, &saddr, NULL);
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if (ret < 0)
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goto out_unlock;
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