From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Tue, 29 May 2018 22:41:20 -0700 From: "Darrick J. Wong" To: Christoph Hellwig Cc: linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 05/34] fs: use ->is_partially_uptodate in page_cache_seek_hole_data Message-ID: <20180530054120.GT30110@magnolia> References: <20180523144357.18985-1-hch@lst.de> <20180523144357.18985-6-hch@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180523144357.18985-6-hch@lst.de> Sender: owner-linux-mm@kvack.org List-ID: On Wed, May 23, 2018 at 04:43:28PM +0200, Christoph Hellwig wrote: > This way the implementation doesn't depend on buffer_head internals. > > Signed-off-by: Christoph Hellwig Looks ok, Reviewed-by: Darrick J. Wong --D > --- > fs/iomap.c | 85 +++++++++++++++++++++++++----------------------------- > 1 file changed, 39 insertions(+), 46 deletions(-) > > diff --git a/fs/iomap.c b/fs/iomap.c > index bef5e91d40bf..0900da23172c 100644 > --- a/fs/iomap.c > +++ b/fs/iomap.c > @@ -589,36 +589,51 @@ int iomap_fiemap(struct inode *inode, struct fiemap_extent_info *fi, > } > EXPORT_SYMBOL_GPL(iomap_fiemap); > > -/* > - * Seek for SEEK_DATA / SEEK_HOLE within @page, starting at @lastoff. > - * > - * Returns the offset within the file on success, and -ENOENT otherwise. > - */ > -static loff_t > -page_seek_hole_data(struct page *page, loff_t lastoff, int whence) > +static bool > +page_seek_hole_data(struct inode *inode, struct page *page, loff_t *lastoff, > + int whence) > { > - loff_t offset = page_offset(page); > - struct buffer_head *bh, *head; > + const struct address_space_operations *ops = inode->i_mapping->a_ops; > + unsigned int bsize = i_blocksize(inode), off; > bool seek_data = whence == SEEK_DATA; > + loff_t poff = page_offset(page); > > - if (lastoff < offset) > - lastoff = offset; > - > - bh = head = page_buffers(page); > - do { > - offset += bh->b_size; > - if (lastoff >= offset) > - continue; > + if (WARN_ON_ONCE(*lastoff >= poff + PAGE_SIZE)) > + return false; > > + if (*lastoff < poff) { > /* > - * Any buffer with valid data in it should have BH_Uptodate set. > + * Last offset smaller than the start of the page means we found > + * a hole: > */ > - if (buffer_uptodate(bh) == seek_data) > - return lastoff; > + if (whence == SEEK_HOLE) > + return true; > + *lastoff = poff; > + } > + > + /* > + * Just check the page unless we can and should check block ranges: > + */ > + if (bsize == PAGE_SIZE || !ops->is_partially_uptodate) > + return PageUptodate(page) == seek_data; > > - lastoff = offset; > - } while ((bh = bh->b_this_page) != head); > - return -ENOENT; > + lock_page(page); > + if (unlikely(page->mapping != inode->i_mapping)) > + goto out_unlock_not_found; > + > + for (off = 0; off < PAGE_SIZE; off += bsize) { > + if ((*lastoff & ~PAGE_MASK) >= off + bsize) > + continue; > + if (ops->is_partially_uptodate(page, off, bsize) == seek_data) { > + unlock_page(page); > + return true; > + } > + *lastoff = poff + off + bsize; > + } > + > +out_unlock_not_found: > + unlock_page(page); > + return false; > } > > /* > @@ -655,30 +670,8 @@ page_cache_seek_hole_data(struct inode *inode, loff_t offset, loff_t length, > for (i = 0; i < nr_pages; i++) { > struct page *page = pvec.pages[i]; > > - /* > - * At this point, the page may be truncated or > - * invalidated (changing page->mapping to NULL), or > - * even swizzled back from swapper_space to tmpfs file > - * mapping. However, page->index will not change > - * because we have a reference on the page. > - * > - * If current page offset is beyond where we've ended, > - * we've found a hole. > - */ > - if (whence == SEEK_HOLE && > - lastoff < page_offset(page)) > + if (page_seek_hole_data(inode, page, &lastoff, whence)) > goto check_range; > - > - lock_page(page); > - if (likely(page->mapping == inode->i_mapping) && > - page_has_buffers(page)) { > - lastoff = page_seek_hole_data(page, lastoff, whence); > - if (lastoff >= 0) { > - unlock_page(page); > - goto check_range; > - } > - } > - unlock_page(page); > lastoff = page_offset(page) + PAGE_SIZE; > } > pagevec_release(&pvec); > -- > 2.17.0 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-xfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html