[PATCH] dax: Fix inefficiency in dax_writeback_mapping_range()

[PATCH] dax: Fix inefficiency in dax_writeback_mapping_range()

[Jan Kara]

dax_writeback_mapping_range() fails to update iteration index when
searching radix tree for entries needing cache flushing. Thus each
pagevec worth of entries is searched starting from the start which is
inefficient and prone to livelocks. Update index properly.

CC: stable@vger.kernel.org
Fixes: 9973c98ecfda3a1dfcab981665b5f1e39bcde64a
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/dax.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/dax.c b/fs/dax.c
index 2a6889b3585f..9187f3b07f3e 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -859,6 +859,7 @@ int dax_writeback_mapping_range(struct address_space *mapping,
 			if (ret < 0)
 				goto out;
 		}
+		start_index = indices[pvec.nr - 1] + 1;
 	}
 out:
 	put_dax(dax_dev);
-- 
2.12.3

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[PATCH] dax: Fix inefficiency in dax_writeback_mapping_range()

[Jan Kara]

dax_writeback_mapping_range() fails to update iteration index when
searching radix tree for entries needing cache flushing. Thus each
pagevec worth of entries is searched starting from the start which is
inefficient and prone to livelocks. Update index properly.

CC: stable@vger.kernel.org
Fixes: 9973c98ecfda3a1dfcab981665b5f1e39bcde64a
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/dax.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/dax.c b/fs/dax.c
index 2a6889b3585f..9187f3b07f3e 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -859,6 +859,7 @@ int dax_writeback_mapping_range(struct address_space *mapping,
 			if (ret < 0)
 				goto out;
 		}
+		start_index = indices[pvec.nr - 1] + 1;
 	}
 out:
 	put_dax(dax_dev);
-- 
2.12.3

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[PATCH] dax: Fix inefficiency in dax_writeback_mapping_range()

[Jan Kara]

dax_writeback_mapping_range() fails to update iteration index when
searching radix tree for entries needing cache flushing. Thus each
pagevec worth of entries is searched starting from the start which is
inefficient and prone to livelocks. Update index properly.

CC: stable@vger.kernel.org
Fixes: 9973c98ecfda3a1dfcab981665b5f1e39bcde64a
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/dax.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/dax.c b/fs/dax.c
index 2a6889b3585f..9187f3b07f3e 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -859,6 +859,7 @@ int dax_writeback_mapping_range(struct address_space *mapping,
 			if (ret < 0)
 				goto out;
 		}
+		start_index = indices[pvec.nr - 1] + 1;
 	}
 out:
 	put_dax(dax_dev);
-- 
2.12.3

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Re: [PATCH] dax: Fix inefficiency in dax_writeback_mapping_range()

[Ross Zwisler]

On Mon, Jun 19, 2017 at 02:45:31PM +0200, Jan Kara wrote:
> dax_writeback_mapping_range() fails to update iteration index when
> searching radix tree for entries needing cache flushing. Thus each
> pagevec worth of entries is searched starting from the start which is
> inefficient and prone to livelocks. Update index properly.
> 
> CC: stable@vger.kernel.org
> Fixes: 9973c98ecfda3a1dfcab981665b5f1e39bcde64a
> Signed-off-by: Jan Kara <jack@suse.cz>

Yep, this seems good, thanks.

Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
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Re: [PATCH] dax: Fix inefficiency in dax_writeback_mapping_range()

[Ross Zwisler]

On Mon, Jun 19, 2017 at 02:45:31PM +0200, Jan Kara wrote:
> dax_writeback_mapping_range() fails to update iteration index when
> searching radix tree for entries needing cache flushing. Thus each
> pagevec worth of entries is searched starting from the start which is
> inefficient and prone to livelocks. Update index properly.
> 
> CC: stable@vger.kernel.org
> Fixes: 9973c98ecfda3a1dfcab981665b5f1e39bcde64a
> Signed-off-by: Jan Kara <jack@suse.cz>

Yep, this seems good, thanks.

Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>

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