diff options
| author | David Howells <dhowells@redhat.com> | 2017-11-02 15:27:51 +0000 |
|---|---|---|
| committer | David Howells <dhowells@redhat.com> | 2017-11-13 15:38:19 +0000 |
| commit | 1199db603511d7463d9d3840f96f61967affc766 (patch) | |
| tree | f2f3031337d905ffbfd82ece97b2e89db501df01 /fs/afs | |
| parent | 5f0fc8ba6a1eec510a1e43def48697985d948a2c (diff) | |
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.c | 13 |
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 */ |