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authorMatthew Wilcox (Oracle) <willy@infradead.org>2020-01-17 22:00:41 -0500
committerMatthew Wilcox (Oracle) <willy@infradead.org>2020-01-17 22:33:27 -0500
commit19c30f4dd0923ef191f35c652ee4058e91e89056 (patch)
tree6080ded903efebfd2c32c21b3dccb2ab96075f4a /lib/xarray.c
parent430f24f94c8a174d411a550d7b5529301922e67a (diff)
XArray: Fix xa_find_after with multi-index entries
If the entry is of an order which is a multiple of XA_CHUNK_SIZE, the current detection of sibling entries does not work. Factor out an xas_sibling() function to make xa_find_after() a little more understandable, and write a new implementation that doesn't suffer from the same bug. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: stable@vger.kernel.org
Diffstat (limited to 'lib/xarray.c')
-rw-r--r--lib/xarray.c20
1 files changed, 13 insertions, 7 deletions
diff --git a/lib/xarray.c b/lib/xarray.c
index 6ecf35c2e1da..03300a0d6425 100644
--- a/lib/xarray.c
+++ b/lib/xarray.c
@@ -1826,6 +1826,17 @@ void *xa_find(struct xarray *xa, unsigned long *indexp,
}
EXPORT_SYMBOL(xa_find);
+static bool xas_sibling(struct xa_state *xas)
+{
+ struct xa_node *node = xas->xa_node;
+ unsigned long mask;
+
+ if (!node)
+ return false;
+ mask = (XA_CHUNK_SIZE << node->shift) - 1;
+ return (xas->xa_index & mask) > (xas->xa_offset << node->shift);
+}
+
/**
* xa_find_after() - Search the XArray for a present entry.
* @xa: XArray.
@@ -1860,13 +1871,8 @@ void *xa_find_after(struct xarray *xa, unsigned long *indexp,
entry = xas_find(&xas, max);
if (xas.xa_node == XAS_BOUNDS)
break;
- if (xas.xa_shift) {
- if (xas.xa_index & ((1UL << xas.xa_shift) - 1))
- continue;
- } else {
- if (xas.xa_offset < (xas.xa_index & XA_CHUNK_MASK))
- continue;
- }
+ if (xas_sibling(&xas))
+ continue;
if (!xas_retry(&xas, entry))
break;
}