From 19c30f4dd0923ef191f35c652ee4058e91e89056 Mon Sep 17 00:00:00 2001 From: "Matthew Wilcox (Oracle)" Date: Fri, 17 Jan 2020 22:00:41 -0500 Subject: 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) Cc: stable@vger.kernel.org --- lib/xarray.c | 20 +++++++++++++------- 1 file changed, 13 insertions(+), 7 deletions(-) (limited to 'lib/xarray.c') 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; } -- cgit