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| author | Matthew Wilcox (Oracle) <willy@infradead.org> | 2020-01-17 22:00:41 -0500 |
|---|---|---|
| committer | Matthew Wilcox (Oracle) <willy@infradead.org> | 2020-01-17 22:33:27 -0500 |
| commit | 19c30f4dd0923ef191f35c652ee4058e91e89056 (patch) | |
| tree | 6080ded903efebfd2c32c21b3dccb2ab96075f4a /lib/xarray.c | |
| parent | 430f24f94c8a174d411a550d7b5529301922e67a (diff) | |
| download | lwn-19c30f4dd0923ef191f35c652ee4058e91e89056.tar.gz lwn-19c30f4dd0923ef191f35c652ee4058e91e89056.zip | |
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.c | 20 |
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; } |