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authorDavid Howells <dhowells@redhat.com>2017-11-02 15:27:51 +0000
committerDavid Howells <dhowells@redhat.com>2017-11-13 15:38:19 +0000
commit1199db603511d7463d9d3840f96f61967affc766 (patch)
treef2f3031337d905ffbfd82ece97b2e89db501df01 /fs/afs
parent5f0fc8ba6a1eec510a1e43def48697985d948a2c (diff)
downloadlinux-1199db603511d7463d9d3840f96f61967affc766.tar.bz2
afs: Fix total-length calculation for multiple-page send
Fix the total-length calculation in afs_make_call() when the operation being dispatched has data from a series of pages attached. Despite the patched code looking like that it should reduce mathematically to the current code, it doesn't because the 32-bit unsigned arithmetic being used to calculate the page-offset-difference doesn't correctly extend to a 64-bit value when the result is effectively negative. Without this, some FS.StoreData operations that span multiple pages fail, reporting too little or too much data. Signed-off-by: David Howells <dhowells@redhat.com>
Diffstat (limited to 'fs/afs')
-rw-r--r--fs/afs/rxrpc.c13
1 files changed, 11 insertions, 2 deletions
diff --git a/fs/afs/rxrpc.c b/fs/afs/rxrpc.c
index 21f43d3acb91..1d075696bf55 100644
--- a/fs/afs/rxrpc.c
+++ b/fs/afs/rxrpc.c
@@ -350,8 +350,17 @@ long afs_make_call(struct afs_addr_cursor *ac, struct afs_call *call,
*/
tx_total_len = call->request_size;
if (call->send_pages) {
- tx_total_len += call->last_to - call->first_offset;
- tx_total_len += (call->last - call->first) * PAGE_SIZE;
+ if (call->last == call->first) {
+ tx_total_len += call->last_to - call->first_offset;
+ } else {
+ /* It looks mathematically like you should be able to
+ * combine the following lines with the ones above, but
+ * unsigned arithmetic is fun when it wraps...
+ */
+ tx_total_len += PAGE_SIZE - call->first_offset;
+ tx_total_len += call->last_to;
+ tx_total_len += (call->last - call->first - 1) * PAGE_SIZE;
+ }
}
/* create a call */