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-rw-r--r--mm/filemap.c7
-rw-r--r--mm/readahead.c30
2 files changed, 19 insertions, 18 deletions
diff --git a/mm/filemap.c b/mm/filemap.c
index 07f5b77114a3..5631d6b2a62d 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -877,8 +877,8 @@ void do_generic_mapping_read(struct address_space *mapping,
877 cached_page = NULL; 877 cached_page = NULL;
878 index = *ppos >> PAGE_CACHE_SHIFT; 878 index = *ppos >> PAGE_CACHE_SHIFT;
879 next_index = index; 879 next_index = index;
880 prev_index = ra.prev_page; 880 prev_index = ra.prev_index;
881 prev_offset = ra.offset; 881 prev_offset = ra.prev_offset;
882 last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT; 882 last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
883 offset = *ppos & ~PAGE_CACHE_MASK; 883 offset = *ppos & ~PAGE_CACHE_MASK;
884 884
@@ -947,7 +947,8 @@ page_ok:
947 offset += ret; 947 offset += ret;
948 index += offset >> PAGE_CACHE_SHIFT; 948 index += offset >> PAGE_CACHE_SHIFT;
949 offset &= ~PAGE_CACHE_MASK; 949 offset &= ~PAGE_CACHE_MASK;
950 prev_offset = ra.offset = offset; 950 prev_offset = offset;
951 ra.prev_offset = offset;
951 952
952 page_cache_release(page); 953 page_cache_release(page);
953 if (ret == nr && desc->count) 954 if (ret == nr && desc->count)
diff --git a/mm/readahead.c b/mm/readahead.c
index 0a6fed9d365c..9861e883fe57 100644
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -37,7 +37,7 @@ void
37file_ra_state_init(struct file_ra_state *ra, struct address_space *mapping) 37file_ra_state_init(struct file_ra_state *ra, struct address_space *mapping)
38{ 38{
39 ra->ra_pages = mapping->backing_dev_info->ra_pages; 39 ra->ra_pages = mapping->backing_dev_info->ra_pages;
40 ra->prev_page = -1; 40 ra->prev_index = -1;
41} 41}
42EXPORT_SYMBOL_GPL(file_ra_state_init); 42EXPORT_SYMBOL_GPL(file_ra_state_init);
43 43
@@ -202,19 +202,19 @@ out:
202 * size: Number of pages in that read 202 * size: Number of pages in that read
203 * Together, these form the "current window". 203 * Together, these form the "current window".
204 * Together, start and size represent the `readahead window'. 204 * Together, start and size represent the `readahead window'.
205 * prev_page: The page which the readahead algorithm most-recently inspected. 205 * prev_index: The page which the readahead algorithm most-recently inspected.
206 * It is mainly used to detect sequential file reading. 206 * It is mainly used to detect sequential file reading.
207 * If page_cache_readahead sees that it is again being called for 207 * If page_cache_readahead sees that it is again being called for
208 * a page which it just looked at, it can return immediately without 208 * a page which it just looked at, it can return immediately without
209 * making any state changes. 209 * making any state changes.
210 * offset: Offset in the prev_page where the last read ended - used for 210 * offset: Offset in the prev_index where the last read ended - used for
211 * detection of sequential file reading. 211 * detection of sequential file reading.
212 * ahead_start, 212 * ahead_start,
213 * ahead_size: Together, these form the "ahead window". 213 * ahead_size: Together, these form the "ahead window".
214 * ra_pages: The externally controlled max readahead for this fd. 214 * ra_pages: The externally controlled max readahead for this fd.
215 * 215 *
216 * When readahead is in the off state (size == 0), readahead is disabled. 216 * When readahead is in the off state (size == 0), readahead is disabled.
217 * In this state, prev_page is used to detect the resumption of sequential I/O. 217 * In this state, prev_index is used to detect the resumption of sequential I/O.
218 * 218 *
219 * The readahead code manages two windows - the "current" and the "ahead" 219 * The readahead code manages two windows - the "current" and the "ahead"
220 * windows. The intent is that while the application is walking the pages 220 * windows. The intent is that while the application is walking the pages
@@ -417,7 +417,7 @@ static int make_ahead_window(struct address_space *mapping, struct file *filp,
417 ra->ahead_size = get_next_ra_size(ra); 417 ra->ahead_size = get_next_ra_size(ra);
418 ra->ahead_start = ra->start + ra->size; 418 ra->ahead_start = ra->start + ra->size;
419 419
420 block = force || (ra->prev_page >= ra->ahead_start); 420 block = force || (ra->prev_index >= ra->ahead_start);
421 ret = blockable_page_cache_readahead(mapping, filp, 421 ret = blockable_page_cache_readahead(mapping, filp,
422 ra->ahead_start, ra->ahead_size, ra, block); 422 ra->ahead_start, ra->ahead_size, ra, block);
423 423
@@ -469,13 +469,13 @@ page_cache_readahead(struct address_space *mapping, struct file_ra_state *ra,
469 * We avoid doing extra work and bogusly perturbing the readahead 469 * We avoid doing extra work and bogusly perturbing the readahead
470 * window expansion logic. 470 * window expansion logic.
471 */ 471 */
472 if (offset == ra->prev_page && --req_size) 472 if (offset == ra->prev_index && --req_size)
473 ++offset; 473 ++offset;
474 474
475 /* Note that prev_page == -1 if it is a first read */ 475 /* Note that prev_index == -1 if it is a first read */
476 sequential = (offset == ra->prev_page + 1); 476 sequential = (offset == ra->prev_index + 1);
477 ra->prev_page = offset; 477 ra->prev_index = offset;
478 ra->offset = 0; 478 ra->prev_offset = 0;
479 479
480 max = get_max_readahead(ra); 480 max = get_max_readahead(ra);
481 newsize = min(req_size, max); 481 newsize = min(req_size, max);
@@ -484,7 +484,7 @@ page_cache_readahead(struct address_space *mapping, struct file_ra_state *ra,
484 if (newsize == 0 || (ra->flags & RA_FLAG_INCACHE)) 484 if (newsize == 0 || (ra->flags & RA_FLAG_INCACHE))
485 goto out; 485 goto out;
486 486
487 ra->prev_page += newsize - 1; 487 ra->prev_index += newsize - 1;
488 488
489 /* 489 /*
490 * Special case - first read at start of file. We'll assume it's 490 * Special case - first read at start of file. We'll assume it's
@@ -540,18 +540,18 @@ page_cache_readahead(struct address_space *mapping, struct file_ra_state *ra,
540 * we get called back on the first page of the ahead window which 540 * we get called back on the first page of the ahead window which
541 * will allow us to submit more IO. 541 * will allow us to submit more IO.
542 */ 542 */
543 if (ra->prev_page >= ra->ahead_start) { 543 if (ra->prev_index >= ra->ahead_start) {
544 ra->start = ra->ahead_start; 544 ra->start = ra->ahead_start;
545 ra->size = ra->ahead_size; 545 ra->size = ra->ahead_size;
546 make_ahead_window(mapping, filp, ra, 0); 546 make_ahead_window(mapping, filp, ra, 0);
547recheck: 547recheck:
548 /* prev_page shouldn't overrun the ahead window */ 548 /* prev_index shouldn't overrun the ahead window */
549 ra->prev_page = min(ra->prev_page, 549 ra->prev_index = min(ra->prev_index,
550 ra->ahead_start + ra->ahead_size - 1); 550 ra->ahead_start + ra->ahead_size - 1);
551 } 551 }
552 552
553out: 553out:
554 return ra->prev_page + 1; 554 return ra->prev_index + 1;
555} 555}
556EXPORT_SYMBOL_GPL(page_cache_readahead); 556EXPORT_SYMBOL_GPL(page_cache_readahead);
557 557