Messages in this thread |  | | Date | Wed, 25 Oct 2000 10:27:23 -0400 (EDT) | From | Alexander Viro <> | Subject | [potential bug] generic_file_readahead() |
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In generic_file_readahead():
unsigned long end_index = inode->i_size >> PAGE_CACHE_SHIFT; unsigned long index = page->index; ... max_ahead = 0; ... raend = index; if (raend < end_index) max_ahead = filp->f_ramax; and later ahead = 0; while (ahead < max_ahead) { ahead ++; if ((raend + ahead) >= end_index) break; if (page_cache_read(filp, raend + ahead) < 0) break; }
AFAICS it means that we have off-by-partial here - if the file size is not a multiple of PAGE_CACHE_SIZE we are missing the last page. Proposed fix: make end_index = (inode->i_size + PAGE_CACHE_SIZE - 1)>>PAGE_CACHE_SHIFT;
Objections?
PS: folks, could those who wrote that function comment on the readahead rules in general? This stuff looks really ugly (presumably from the layers and layers of small modifications) and comments on _intentions_ of that code (as opposed to "what are we doing in the next two lines") would be very welcome.
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