From 80b435a3f35795600654e9705f4b3fbbcc427a9d Mon Sep 17 00:00:00 2001 From: Arpad Horvath Date: Fri, 14 Feb 2014 16:42:27 -0800 Subject: [PATCH] sdcard: direct I/O file access fix If a file is opened in direct I/O mode (with O_DIRECT flag), the read buffer addess must be aligned to memory page size boundary. The Direct I/O is not needed for normal files, however, some special hardware access (e.g. smart SD cards) will not work without it. Change-Id: I42babeee86dba1880fd23e2592fddd7060da3e20 --- sdcard/sdcard.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/sdcard/sdcard.c b/sdcard/sdcard.c index 4722708f3..3bc8cd3f7 100644 --- a/sdcard/sdcard.c +++ b/sdcard/sdcard.c @@ -232,7 +232,7 @@ struct fuse_handler { * buffer at the same time. This allows us to share the underlying storage. */ union { __u8 request_buffer[MAX_REQUEST_SIZE]; - __u8 read_buffer[MAX_READ]; + __u8 read_buffer[MAX_READ + PAGESIZE]; }; }; @@ -1218,6 +1218,7 @@ static int handle_read(struct fuse* fuse, struct fuse_handler* handler, __u32 size = req->size; __u64 offset = req->offset; int res; + __u8 *read_buffer = (__u8 *) ((uintptr_t)(handler->read_buffer + PAGESIZE) & ~((uintptr_t)PAGESIZE-1)); /* Don't access any other fields of hdr or req beyond this point, the read buffer * overlaps the request buffer and will clobber data in the request. This @@ -1225,14 +1226,14 @@ static int handle_read(struct fuse* fuse, struct fuse_handler* handler, TRACE("[%d] READ %p(%d) %u@%llu\n", handler->token, h, h->fd, size, offset); - if (size > sizeof(handler->read_buffer)) { + if (size > MAX_READ) { return -EINVAL; } - res = pread64(h->fd, handler->read_buffer, size, offset); + res = pread64(h->fd, read_buffer, size, offset); if (res < 0) { return -errno; } - fuse_reply(fuse, unique, handler->read_buffer, res); + fuse_reply(fuse, unique, read_buffer, res); return NO_STATUS; }