From: Christoph Hellwig Subject: [PATCH 5/6] xfs: Switch to iomap for SEEK_HOLE / SEEK_DATA Date: Tue, 27 Jun 2017 14:48:27 -0700 Message-ID: <20170627214828.1029-6-hch@lst.de> References: <20170627214828.1029-1-hch@lst.de> Cc: Jan Kara , linux-fsdevel@vger.kernel.org, linux-xfs@vger.kernel.org, linux-ext4@vger.kernel.org To: Andreas Gruenbacher Return-path: In-Reply-To: <20170627214828.1029-1-hch@lst.de> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org Switch to the iomap_seek_hole and iomap_seek_data helpers for implementing lseek SEEK_HOLE / SEEK_DATA, and remove all the code that isn't needed any more. Based on patches from Andreas Gruenbacher . Signed-off-by: Christoph Hellwig --- fs/xfs/xfs_file.c | 375 ++--------------------------------------------------- fs/xfs/xfs_inode.h | 3 - 2 files changed, 14 insertions(+), 364 deletions(-) diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c index 36c129303fcf..280f07a73d57 100644 --- a/fs/xfs/xfs_file.c +++ b/fs/xfs/xfs_file.c @@ -953,378 +953,31 @@ xfs_file_readdir( return xfs_readdir(NULL, ip, ctx, bufsize); } -/* - * This type is designed to indicate the type of offset we would like - * to search from page cache for xfs_seek_hole_data(). - */ -enum { - HOLE_OFF = 0, - DATA_OFF, -}; - -/* - * Lookup the desired type of offset from the given page. - * - * On success, return true and the offset argument will point to the - * start of the region that was found. Otherwise this function will - * return false and keep the offset argument unchanged. - */ -STATIC bool -xfs_lookup_buffer_offset( - struct page *page, - loff_t *offset, - unsigned int type) -{ - loff_t lastoff = page_offset(page); - bool found = false; - struct buffer_head *bh, *head; - - bh = head = page_buffers(page); - do { - /* - * Unwritten extents that have data in the page - * cache covering them can be identified by the - * BH_Unwritten state flag. Pages with multiple - * buffers might have a mix of holes, data and - * unwritten extents - any buffer with valid - * data in it should have BH_Uptodate flag set - * on it. - */ - if (buffer_unwritten(bh) || - buffer_uptodate(bh)) { - if (type == DATA_OFF) - found = true; - } else { - if (type == HOLE_OFF) - found = true; - } - - if (found) { - *offset = lastoff; - break; - } - lastoff += bh->b_size; - } while ((bh = bh->b_this_page) != head); - - return found; -} - -/* - * This routine is called to find out and return a data or hole offset - * from the page cache for unwritten extents according to the desired - * type for xfs_seek_hole_data(). - * - * The argument offset is used to tell where we start to search from the - * page cache. Map is used to figure out the end points of the range to - * lookup pages. - * - * Return true if the desired type of offset was found, and the argument - * offset is filled with that address. Otherwise, return false and keep - * offset unchanged. - */ -STATIC bool -xfs_find_get_desired_pgoff( - struct inode *inode, - struct xfs_bmbt_irec *map, - unsigned int type, - loff_t *offset) -{ - struct xfs_inode *ip = XFS_I(inode); - struct xfs_mount *mp = ip->i_mount; - struct pagevec pvec; - pgoff_t index; - pgoff_t end; - loff_t endoff; - loff_t startoff = *offset; - loff_t lastoff = startoff; - bool found = false; - - pagevec_init(&pvec, 0); - - index = startoff >> PAGE_SHIFT; - endoff = XFS_FSB_TO_B(mp, map->br_startoff + map->br_blockcount); - end = (endoff - 1) >> PAGE_SHIFT; - do { - int want; - unsigned nr_pages; - unsigned int i; - - want = min_t(pgoff_t, end - index, PAGEVEC_SIZE - 1) + 1; - nr_pages = pagevec_lookup(&pvec, inode->i_mapping, index, - want); - if (nr_pages == 0) - break; - - for (i = 0; i < nr_pages; i++) { - struct page *page = pvec.pages[i]; - loff_t b_offset; - - /* - * 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 (type == HOLE_OFF && lastoff < endoff && - lastoff < page_offset(pvec.pages[i])) { - found = true; - *offset = lastoff; - goto out; - } - /* Searching done if the page index is out of range. */ - if (page->index > end) - goto out; - - lock_page(page); - /* - * Page truncated or invalidated(page->mapping == NULL). - * We can freely skip it and proceed to check the next - * page. - */ - if (unlikely(page->mapping != inode->i_mapping)) { - unlock_page(page); - continue; - } - - if (!page_has_buffers(page)) { - unlock_page(page); - continue; - } - - found = xfs_lookup_buffer_offset(page, &b_offset, type); - if (found) { - /* - * The found offset may be less than the start - * point to search if this is the first time to - * come here. - */ - *offset = max_t(loff_t, startoff, b_offset); - unlock_page(page); - goto out; - } - - /* - * We either searching data but nothing was found, or - * searching hole but found a data buffer. In either - * case, probably the next page contains the desired - * things, update the last offset to it so. - */ - lastoff = page_offset(page) + PAGE_SIZE; - unlock_page(page); - } - - /* - * The number of returned pages less than our desired, search - * done. - */ - if (nr_pages < want) - break; - - index = pvec.pages[i - 1]->index + 1; - pagevec_release(&pvec); - } while (index <= end); - - /* No page at lastoff and we are not done - we found a hole. */ - if (type == HOLE_OFF && lastoff < endoff) { - *offset = lastoff; - found = true; - } -out: - pagevec_release(&pvec); - return found; -} - -/* - * caller must lock inode with xfs_ilock_data_map_shared, - * can we craft an appropriate ASSERT? - * - * end is because the VFS-level lseek interface is defined such that any - * offset past i_size shall return -ENXIO, but we use this for quota code - * which does not maintain i_size, and we want to SEEK_DATA past i_size. - */ -loff_t -__xfs_seek_hole_data( - struct inode *inode, - loff_t start, - loff_t end, - int whence) -{ - struct xfs_inode *ip = XFS_I(inode); - struct xfs_mount *mp = ip->i_mount; - loff_t uninitialized_var(offset); - xfs_fileoff_t fsbno; - xfs_filblks_t lastbno; - int error; - - if (start >= end) { - error = -ENXIO; - goto out_error; - } - - /* - * Try to read extents from the first block indicated - * by fsbno to the end block of the file. - */ - fsbno = XFS_B_TO_FSBT(mp, start); - lastbno = XFS_B_TO_FSB(mp, end); - - for (;;) { - struct xfs_bmbt_irec map[2]; - int nmap = 2; - unsigned int i; - - error = xfs_bmapi_read(ip, fsbno, lastbno - fsbno, map, &nmap, - XFS_BMAPI_ENTIRE); - if (error) - goto out_error; - - /* No extents at given offset, must be beyond EOF */ - if (nmap == 0) { - error = -ENXIO; - goto out_error; - } - - for (i = 0; i < nmap; i++) { - offset = max_t(loff_t, start, - XFS_FSB_TO_B(mp, map[i].br_startoff)); - - /* Landed in the hole we wanted? */ - if (whence == SEEK_HOLE && - map[i].br_startblock == HOLESTARTBLOCK) - goto out; - - /* Landed in the data extent we wanted? */ - if (whence == SEEK_DATA && - (map[i].br_startblock == DELAYSTARTBLOCK || - (map[i].br_state == XFS_EXT_NORM && - !isnullstartblock(map[i].br_startblock)))) - goto out; - - /* - * Landed in an unwritten extent, try to search - * for hole or data from page cache. - */ - if (map[i].br_state == XFS_EXT_UNWRITTEN) { - if (xfs_find_get_desired_pgoff(inode, &map[i], - whence == SEEK_HOLE ? HOLE_OFF : DATA_OFF, - &offset)) - goto out; - } - } - - /* - * We only received one extent out of the two requested. This - * means we've hit EOF and didn't find what we are looking for. - */ - if (nmap == 1) { - /* - * If we were looking for a hole, set offset to - * the end of the file (i.e., there is an implicit - * hole at the end of any file). - */ - if (whence == SEEK_HOLE) { - offset = end; - break; - } - /* - * If we were looking for data, it's nowhere to be found - */ - ASSERT(whence == SEEK_DATA); - error = -ENXIO; - goto out_error; - } - - ASSERT(i > 1); - - /* - * Nothing was found, proceed to the next round of search - * if the next reading offset is not at or beyond EOF. - */ - fsbno = map[i - 1].br_startoff + map[i - 1].br_blockcount; - start = XFS_FSB_TO_B(mp, fsbno); - if (start >= end) { - if (whence == SEEK_HOLE) { - offset = end; - break; - } - ASSERT(whence == SEEK_DATA); - error = -ENXIO; - goto out_error; - } - } - -out: - /* - * If at this point we have found the hole we wanted, the returned - * offset may be bigger than the file size as it may be aligned to - * page boundary for unwritten extents. We need to deal with this - * situation in particular. - */ - if (whence == SEEK_HOLE) - offset = min_t(loff_t, offset, end); - - return offset; - -out_error: - return error; -} - -STATIC loff_t -xfs_seek_hole_data( - struct file *file, - loff_t start, - int whence) -{ - struct inode *inode = file->f_mapping->host; - struct xfs_inode *ip = XFS_I(inode); - struct xfs_mount *mp = ip->i_mount; - uint lock; - loff_t offset, end; - int error = 0; - - if (XFS_FORCED_SHUTDOWN(mp)) - return -EIO; - - lock = xfs_ilock_data_map_shared(ip); - - end = i_size_read(inode); - offset = __xfs_seek_hole_data(inode, start, end, whence); - if (offset < 0) { - error = offset; - goto out_unlock; - } - - offset = vfs_setpos(file, offset, inode->i_sb->s_maxbytes); - -out_unlock: - xfs_iunlock(ip, lock); - - if (error) - return error; - return offset; -} - STATIC loff_t xfs_file_llseek( struct file *file, loff_t offset, int whence) { + struct inode *inode = file->f_mapping->host; + + if (XFS_FORCED_SHUTDOWN(XFS_I(inode)->i_mount)) + return -EIO; + switch (whence) { - case SEEK_END: - case SEEK_CUR: - case SEEK_SET: + default: return generic_file_llseek(file, offset, whence); case SEEK_HOLE: + offset = iomap_seek_hole(inode, offset, &xfs_iomap_ops); + break; case SEEK_DATA: - return xfs_seek_hole_data(file, offset, whence); - default: - return -EINVAL; + offset = iomap_seek_data(inode, offset, &xfs_iomap_ops); + break; } + + if (offset < 0) + return offset; + return vfs_setpos(file, offset, inode->i_sb->s_maxbytes); } /* diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h index 677d0bfe1c2d..0ee453de239a 100644 --- a/fs/xfs/xfs_inode.h +++ b/fs/xfs/xfs_inode.h @@ -445,9 +445,6 @@ int xfs_zero_eof(struct xfs_inode *ip, xfs_off_t offset, xfs_fsize_t isize, bool *did_zeroing); int xfs_zero_range(struct xfs_inode *ip, xfs_off_t pos, xfs_off_t count, bool *did_zero); -loff_t __xfs_seek_hole_data(struct inode *inode, loff_t start, - loff_t eof, int whence); - /* from xfs_iops.c */ extern void xfs_setup_inode(struct xfs_inode *ip); -- 2.11.0