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SubjectRe: [RFC v11][PATCH 03/13] General infrastructure for checkpoint restart
Oren Laadan wrote:

> +/*
> + * Helpers to write(read) from(to) kernel space to(from) the checkpoint
> + * image file descriptor (similar to how a core-dump is performed).
> + *
> + * cr_kwrite() - write a kernel-space buffer to the checkpoint image
> + * cr_kread() - read from the checkpoint image to a kernel-space buffer
> + */
> +
> +int cr_kwrite(struct cr_ctx *ctx, void *addr, int count)
> +{
> + struct file *file = ctx->file;
> + mm_segment_t fs;
> + ssize_t nwrite;
> + int nleft;
> +
> + fs = get_fs();
> + set_fs(KERNEL_DS);
> + for (nleft = count; nleft; nleft -= nwrite) {
> + nwrite = file->f_op->write(file, addr, nleft, &file->f_pos);
> + if (nwrite < 0) {
> + if (nwrite == -EAGAIN)
> + nwrite = 0;
> + else

set_fs(fs) here

> + return nwrite;
> + }
> + addr += nwrite;
> + }
> + set_fs(fs);
> + ctx->total += count;
> + return 0;
> +}
> +
> +int cr_kread(struct cr_ctx *ctx, void *addr, int count)
> +{
> + struct file *file = ctx->file;
> + mm_segment_t fs;
> + ssize_t nread;
> + int nleft;
> +
> + fs = get_fs();
> + set_fs(KERNEL_DS);
> + for (nleft = count; nleft; nleft -= nread) {
> + nread = file->f_op->read(file, addr, nleft, &file->f_pos);
> + if (nread <= 0) {
> + if (nread == -EAGAIN) {
> + nread = 0;
> + continue;
> + } else if (nread == 0)
> + nread = -EPIPE; /* unexecpted EOF */

set_fs(fs) here as well

> + return nread;
> + }
> + addr += nread;
> + }
> + set_fs(fs);
> + ctx->total += count;
> + return 0;
> +}
> +



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