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| author | Ross Zwisler <ross.zwisler@linux.intel.com> | 2016-08-25 15:17:17 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-09-07 08:34:53 +0200 |
| commit | c46ca4b75de7501d8b78da2aacb41ef06f906677 (patch) | |
| tree | a2d9db57affabfcfb96ad5454a5d896653bfc2e1 /mm | |
| parent | c6115cb45eeecd89151830e693d2b5c83dee7120 (diff) | |
| download | lwn-c46ca4b75de7501d8b78da2aacb41ef06f906677.tar.gz lwn-c46ca4b75de7501d8b78da2aacb41ef06f906677.zip | |
mm: silently skip readahead for DAX inodes
commit 11bd969fdefea3ac0cb9791224f1e09784e21e58 upstream.
For DAX inodes we need to be careful to never have page cache pages in
the mapping->page_tree. This radix tree should be composed only of DAX
exceptional entries and zero pages.
ltp's readahead02 test was triggering a warning because we were trying
to insert a DAX exceptional entry but found that a page cache page had
already been inserted into the tree. This page was being inserted into
the radix tree in response to a readahead(2) call.
Readahead doesn't make sense for DAX inodes, but we don't want it to
report a failure either. Instead, we just return success and don't do
any work.
Link: http://lkml.kernel.org/r/20160824221429.21158-1-ross.zwisler@linux.intel.com
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Reported-by: Jeff Moyer <jmoyer@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Jan Kara <jack@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/readahead.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/mm/readahead.c b/mm/readahead.c index 40be3ae0afe3..7f9f8c3464e2 100644 --- a/mm/readahead.c +++ b/mm/readahead.c @@ -8,6 +8,7 @@ */ #include <linux/kernel.h> +#include <linux/dax.h> #include <linux/gfp.h> #include <linux/export.h> #include <linux/blkdev.h> @@ -545,6 +546,14 @@ do_readahead(struct address_space *mapping, struct file *filp, if (!mapping || !mapping->a_ops) return -EINVAL; + /* + * Readahead doesn't make sense for DAX inodes, but we don't want it + * to report a failure either. Instead, we just return success and + * don't do any work. + */ + if (dax_mapping(mapping)) + return 0; + return force_page_cache_readahead(mapping, filp, index, nr); } |