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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
This commit is contained in:
Arpad Horvath 2014-02-14 16:42:27 -08:00 committed by JP Abgrall
parent d0307beeef
commit 80b435a3f3
1 changed files with 5 additions and 4 deletions
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9
sdcard/sdcard.c
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@ -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;
}