Nick Piggin wrote:
On Mon, Mar 22, 2010 at 08:12:45PM -0400, Oren Laadan wrote:
On Mon, 22 Mar 2010, Nick Piggin wrote:
On Thu, Mar 18, 2010 at 08:59:45PM -0400, Oren Laadan wrote:
These two are used in the next patch when calling vfs_read/write()
Said next patch didn't seem to make it to fsdevel.
Thanks for reviewing, and sorry about this glitch - see below.
Should it at least go to fs/internal.h?
Sure.
So Here is the relevant hunk from said patch (the entire
patch is: https://patchwork.kernel.org/patch/86389/):
+/*
+ * Helpers to write(read) from(to) kernel space to(from) the checkpoint
+ * image file descriptor (similar to how a core-dump is performed).
+ *
+ * ckpt_kwrite() - write a kernel-space buffer to the checkpoint image
+ * ckpt_kread() - read from the checkpoint image to a kernel-space buffer
Hmm, OK. Slightly-more-write(2) type of write.
fs/splice.c code also has a kernel_write and readv. Not sure if there is
any other common code. But maybe it would be better to put together some
useful helpers under fs/ rather than a ckpt specific thing.
Right. Another place is fs/exec.c that provides kernel_read().
I'll put the common code in kernel/read_write.c then.
Oren.
+ */
+
+static inline int _ckpt_kwrite(struct file *file, void *addr, int count)
+{
+ void __user *uaddr = (__force void __user *) addr;
+ ssize_t nwrite;
+ int nleft;
+
+ for (nleft = count; nleft; nleft -= nwrite) {
+ loff_t pos = file_pos_read(file);
+ nwrite = vfs_write(file, uaddr, nleft, &pos);
+ file_pos_write(file, pos);
+ if (nwrite < 0) {
+ if (nwrite == -EAGAIN)
+ nwrite = 0;
+ else
+ return nwrite;
+ }
+ uaddr += nwrite;
+ }
+ return 0;
+}
+
+int ckpt_kwrite(struct ckpt_ctx *ctx, void *addr, int count)
+{
+ mm_segment_t fs;
+ int ret;
+
+ fs = get_fs();
+ set_fs(KERNEL_DS);
+ ret = _ckpt_kwrite(ctx->file, addr, count);
+ set_fs(fs);
+
+ ctx->total += count;
+ return ret;
+}
+
+static inline int _ckpt_kread(struct file *file, void *addr, int count)
+{
+ void __user *uaddr = (__force void __user *) addr;
+ ssize_t nread;
+ int nleft;
+
+ for (nleft = count; nleft; nleft -= nread) {
+ loff_t pos = file_pos_read(file);
+ nread = vfs_read(file, uaddr, nleft, &pos);
+ file_pos_write(file, pos);
+ if (nread <= 0) {
+ if (nread == -EAGAIN) {
+ nread = 0;
+ continue;
+ } else if (nread == 0)
+ nread = -EPIPE; /* unexecpted EOF */
+ return nread;
+ }
+ uaddr += nread;
+ }
+ return 0;
+}
+
+int ckpt_kread(struct ckpt_ctx *ctx, void *addr, int count)
+{
+ mm_segment_t fs;
+ int ret;
+
+ fs = get_fs();
+ set_fs(KERNEL_DS);
+ ret = _ckpt_kread(ctx->file , addr, count);
+ set_fs(fs);
+
+ ctx->total += count;
+ return ret;
+}
Oren.
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