2021년 4월 8일 (목) 오전 12:05, Matthew Wilcox <willy@xxxxxxxxxxxxx>님이 작성: > > > commit 5fdb322ff2c2b4ad519f490dcb7ebb96c5439af7 > Author: Daeho Jeong <daehojeong@xxxxxxxxxx> > Date: Thu Dec 3 15:56:15 2020 +0900 > > f2fs: add F2FS_IOC_DECOMPRESS_FILE and F2FS_IOC_COMPRESS_FILE > > + page_cache_ra_unbounded(&ractl, len, 0); > > /** > * page_cache_ra_unbounded - Start unchecked readahead. > * @ractl: Readahead control. > * @nr_to_read: The number of pages to read. > * @lookahead_size: Where to start the next readahead. > * > * This function is for filesystems to call when they want to start > * readahead beyond a file's stated i_size. This is almost certainly > * not the function you want to call. Use page_cache_async_readahead() > * or page_cache_sync_readahead() instead. > * > * Context: File is referenced by caller. Mutexes may be held by caller. > * May sleep, but will not reenter filesystem to reclaim memory. > */ > > Why? > Hi Matthew, What I wanted here is like do_page_cache_ra(), but do_page_cache_ra() is defined in mm/internal.h only for internal use. So, I used it, because we already checked the i_size boundary on our own. Actually, I wanted to detour the internal readahead mechanism using page_cache_ra_unbounded() to generate cluster size aligned read requests. Plus, page_cache_sync_readahead() is not good for our situation, it might end up with cluster misaligned reads which trigger internal duplicated cluster reads. > > > _______________________________________________ > Linux-f2fs-devel mailing list > Linux-f2fs-devel@xxxxxxxxxxxxxxxxxxxxx > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
