xfs: xfs_seek_data() refinement with unwritten extents check up from page cache (52f1acc8) · Commits · e / devices / android_kernel_oneplus_sm8150

fs/xfs/xfs_file.c

+54 −18

Original line number	Diff line number	Diff line
		@@ -1186,8 +1186,6 @@ xfs_seek_data(
		struct inode *inode = file->f_mapping->host;
		struct xfs_inode *ip = XFS_I(inode);
		struct xfs_mount *mp = ip->i_mount;
		struct xfs_bmbt_irec map[2];
		int nmap = 2;
		loff_t uninitialized_var(offset);
		xfs_fsize_t isize;
		xfs_fileoff_t fsbno;
		@@ -1203,36 +1201,74 @@ xfs_seek_data(
		goto out_unlock;
		}

		fsbno = XFS_B_TO_FSBT(mp, start);

		/*
		* 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);
		end = XFS_B_TO_FSB(mp, isize);
		for (;;) {
		struct xfs_bmbt_irec map[2];
		int nmap = 2;
		unsigned int i;

		error = xfs_bmapi_read(ip, fsbno, end - fsbno, map, &nmap,
		XFS_BMAPI_ENTIRE);
		if (error)
		goto out_unlock;

		/* No extents at given offset, must be beyond EOF */
		if (nmap == 0) {
		error = ENXIO;
		goto out_unlock;
		}

		for (i = 0; i < nmap; i++) {
		offset = max_t(loff_t, start,
		XFS_FSB_TO_B(mp, map[i].br_startoff));

		/* Landed in a data extent */
		if (map[i].br_startblock == DELAYSTARTBLOCK \|\|
		(map[i].br_state == XFS_EXT_NORM &&
		!isnullstartblock(map[i].br_startblock)))
		goto out;

		/*
		* Treat unwritten extent as data extent since it might
		* contains dirty data in page cache.
		* Landed in an unwritten extent, try to search data
		* from page cache.
		*/
		if (map[i].br_state == XFS_EXT_UNWRITTEN) {
		if (xfs_find_get_desired_pgoff(inode, &map[i],
		DATA_OFF, &offset))
		goto out;
		}
		}

		/*
		* map[0] is hole or its an unwritten extent but
		* without data in page cache. Probably means that
		* we are reading after EOF if nothing in map[1].
		*/
		if (map[0].br_startblock != HOLESTARTBLOCK) {
		offset = max_t(loff_t, start,
		XFS_FSB_TO_B(mp, map[0].br_startoff));
		} else {
		if (nmap == 1) {
		error = ENXIO;
		goto out_unlock;
		}

		offset = max_t(loff_t, start,
		XFS_FSB_TO_B(mp, map[1].br_startoff));
		ASSERT(i > 1);

		/*
		* Nothing was found, proceed to the next round of search
		* if reading offset not beyond or hit EOF.
		*/
		fsbno = map[i - 1].br_startoff + map[i - 1].br_blockcount;
		start = XFS_FSB_TO_B(mp, fsbno);
		if (start >= isize) {
		error = ENXIO;
		goto out_unlock;
		}
		}

		out:
		if (offset != file->f_pos)
		file->f_pos = offset;