Commit 5a5fff60 authored by Mykyta Yatsenko's avatar Mykyta Yatsenko Committed by Alexei Starovoitov
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lib/freader: support reading more than 2 folios 



freader_fetch currently reads from at most two folios. When a read spans
into a third folio, the overflow bytes are copied adjacent to the second
folio’s data instead of being handled as a separate folio.
This patch modifies fetch algorithm to support reading from many folios.

Signed-off-by: default avatarMykyta Yatsenko <yatsenko@meta.com>
Reviewed-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20251026203853.135105-5-mykyta.yatsenko5@gmail.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 76e4fed8

lib/buildid.c

+15 −12
Original line number Diff line number Diff line
@@ -108,18 +108,21 @@ const void *freader_fetch(struct freader *r, loff_t file_off, size_t sz) 
	 */

	folio_sz = folio_size(r->folio);

	if (file_off + sz > r->folio_off + folio_sz) {

		int part_sz = r->folio_off + folio_sz - file_off;

		u64 part_sz = r->folio_off + folio_sz - file_off, off;



		/* copy the part that resides in the current folio */

		memcpy(r->buf, r->addr + (file_off - r->folio_off), part_sz);

		memcpy(r->buf, r->addr + file_off - r->folio_off, part_sz);

		off = part_sz;



		while (off < sz) {

			/* fetch next folio */

			r->err = freader_get_folio(r, r->folio_off + folio_sz);

			if (r->err)

				return NULL;



		/* copy the rest of requested data */

		memcpy(r->buf + part_sz, r->addr, sz - part_sz);

			folio_sz = folio_size(r->folio);

			part_sz = min_t(u64, sz - off, folio_sz);

			memcpy(r->buf + off, r->addr, part_sz);

			off += part_sz;

		}



		return r->buf;

	}