X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=mm%2Freadahead.c;fp=mm%2Freadahead.c;h=0f142a40984b1674228e067f491159d42b13f32d;hb=43bc926fffd92024b46cafaf7350d669ba9ca884;hp=b840e7c6ea740433d1851c379705efe191259e1d;hpb=cee37fe97739d85991964371c1f3a745c00dd236;p=linux-2.6.git diff --git a/mm/readahead.c b/mm/readahead.c index b840e7c6e..0f142a409 100644 --- a/mm/readahead.c +++ b/mm/readahead.c @@ -52,13 +52,24 @@ static inline unsigned long get_min_readahead(struct file_ra_state *ra) return (VM_MIN_READAHEAD * 1024) / PAGE_CACHE_SIZE; } +static inline void reset_ahead_window(struct file_ra_state *ra) +{ + /* + * ... but preserve ahead_start + ahead_size value, + * see 'recheck:' label in page_cache_readahead(). + * Note: We never use ->ahead_size as rvalue without + * checking ->ahead_start != 0 first. + */ + ra->ahead_size += ra->ahead_start; + ra->ahead_start = 0; +} + static inline void ra_off(struct file_ra_state *ra) { ra->start = 0; ra->flags = 0; ra->size = 0; - ra->ahead_start = 0; - ra->ahead_size = 0; + reset_ahead_window(ra); return; } @@ -72,10 +83,10 @@ static unsigned long get_init_ra_size(unsigned long size, unsigned long max) { unsigned long newsize = roundup_pow_of_two(size); - if (newsize <= max / 64) - newsize = newsize * newsize; + if (newsize <= max / 32) + newsize = newsize * 4; else if (newsize <= max / 4) - newsize = max / 4; + newsize = newsize * 2; else newsize = max; return newsize; @@ -158,7 +169,7 @@ static int read_pages(struct address_space *mapping, struct file *filp, { unsigned page_idx; struct pagevec lru_pvec; - int ret = 0; + int ret; if (mapping->a_ops->readpages) { ret = mapping->a_ops->readpages(filp, mapping, pages, nr_pages); @@ -171,14 +182,17 @@ static int read_pages(struct address_space *mapping, struct file *filp, list_del(&page->lru); if (!add_to_page_cache(page, mapping, page->index, GFP_KERNEL)) { - mapping->a_ops->readpage(filp, page); - if (!pagevec_add(&lru_pvec, page)) - __pagevec_lru_add(&lru_pvec); - } else { - page_cache_release(page); + ret = mapping->a_ops->readpage(filp, page); + if (ret != AOP_TRUNCATED_PAGE) { + if (!pagevec_add(&lru_pvec, page)) + __pagevec_lru_add(&lru_pvec); + continue; + } /* else fall through to release */ } + page_cache_release(page); } pagevec_lru_add(&lru_pvec); + ret = 0; out: return ret; } @@ -254,7 +268,7 @@ out: */ static int __do_page_cache_readahead(struct address_space *mapping, struct file *filp, - unsigned long offset, unsigned long nr_to_read) + pgoff_t offset, unsigned long nr_to_read) { struct inode *inode = mapping->host; struct page *page; @@ -274,7 +288,7 @@ __do_page_cache_readahead(struct address_space *mapping, struct file *filp, */ read_lock_irq(&mapping->tree_lock); for (page_idx = 0; page_idx < nr_to_read; page_idx++) { - unsigned long page_offset = offset + page_idx; + pgoff_t page_offset = offset + page_idx; if (page_offset > end_index) break; @@ -311,7 +325,7 @@ out: * memory at once. */ int force_page_cache_readahead(struct address_space *mapping, struct file *filp, - unsigned long offset, unsigned long nr_to_read) + pgoff_t offset, unsigned long nr_to_read) { int ret = 0; @@ -368,7 +382,7 @@ static inline int check_ra_success(struct file_ra_state *ra, * request queues. */ int do_page_cache_readahead(struct address_space *mapping, struct file *filp, - unsigned long offset, unsigned long nr_to_read) + pgoff_t offset, unsigned long nr_to_read) { if (bdi_read_congested(mapping->backing_dev_info)) return -1; @@ -385,7 +399,7 @@ int do_page_cache_readahead(struct address_space *mapping, struct file *filp, */ static int blockable_page_cache_readahead(struct address_space *mapping, struct file *filp, - unsigned long offset, unsigned long nr_to_read, + pgoff_t offset, unsigned long nr_to_read, struct file_ra_state *ra, int block) { int actual; @@ -423,21 +437,33 @@ static int make_ahead_window(struct address_space *mapping, struct file *filp, * congestion. The ahead window will any way be closed * in case we failed due to excessive page cache hits. */ - ra->ahead_start = 0; - ra->ahead_size = 0; + reset_ahead_window(ra); } return ret; } -/* - * page_cache_readahead is the main function. If performs the adaptive +/** + * page_cache_readahead - generic adaptive readahead + * @mapping: address_space which holds the pagecache and I/O vectors + * @ra: file_ra_state which holds the readahead state + * @filp: passed on to ->readpage() and ->readpages() + * @offset: start offset into @mapping, in PAGE_CACHE_SIZE units + * @req_size: hint: total size of the read which the caller is performing in + * PAGE_CACHE_SIZE units + * + * page_cache_readahead() is the main function. If performs the adaptive * readahead window size management and submits the readahead I/O. + * + * Note that @filp is purely used for passing on to the ->readpage[s]() + * handler: it may refer to a different file from @mapping (so we may not use + * @filp->f_mapping or @filp->f_dentry->d_inode here). + * Also, @ra may not be equal to &@filp->f_ra. + * */ unsigned long page_cache_readahead(struct address_space *mapping, struct file_ra_state *ra, - struct file *filp, unsigned long offset, - unsigned long req_size) + struct file *filp, pgoff_t offset, unsigned long req_size) { unsigned long max, newsize; int sequential; @@ -504,11 +530,11 @@ page_cache_readahead(struct address_space *mapping, struct file_ra_state *ra, * If we get here we are doing sequential IO and this was not the first * occurence (ie we have an existing window) */ - if (ra->ahead_start == 0) { /* no ahead window yet */ if (!make_ahead_window(mapping, filp, ra, 0)) - goto out; + goto recheck; } + /* * Already have an ahead window, check if we crossed into it. * If so, shift windows and issue a new ahead window. @@ -520,11 +546,16 @@ page_cache_readahead(struct address_space *mapping, struct file_ra_state *ra, ra->start = ra->ahead_start; ra->size = ra->ahead_size; make_ahead_window(mapping, filp, ra, 0); +recheck: + /* prev_page shouldn't overrun the ahead window */ + ra->prev_page = min(ra->prev_page, + ra->ahead_start + ra->ahead_size - 1); } out: return ra->prev_page + 1; } +EXPORT_SYMBOL_GPL(page_cache_readahead); /* * handle_ra_miss() is called when it is known that a page which should have @@ -540,6 +571,7 @@ void handle_ra_miss(struct address_space *mapping, { ra->flags |= RA_FLAG_MISS; ra->flags &= ~RA_FLAG_INCACHE; + ra->cache_hit = 0; } /*