xfs: refactor the predicate part of xfs_free_eofblocks

Refactor the part of _free_eofblocks that decides if it's really going
to truncate post-EOF blocks into a separate helper function.  The
upcoming deferred inode inactivation patch requires us to be able to
decide this prior to actual inactivation.  No functionality changes.

Signed-off-by: Darrick J. Wong <[email protected]>
(cherry picked from commit 	5dab4f336f751de084ec2e915d2244086fec3559)
cherry-pick-repo=kernel/git/djwong/xfs-linux.git

Orabug: 30898008

Signed-off-by: Junxiao Bi <[email protected]>
Reviewed-by: Darrick J. Wong <[email protected]>
Signed-off-by: Somasundaram Krishnasamy <[email protected]>

Author: djwong

fs/xfs/xfs_bmap_util.c

@@ -815,78 +815,64 @@ xfs_free_eofblocks(
 	struct xfs_inode	*ip)
 {
 	struct xfs_trans	*tp;
-	int			error;
-	xfs_fileoff_t		end_fsb;
-	xfs_fileoff_t		last_fsb;
-	xfs_filblks_t		map_len;
-	int			nimaps;
-	struct xfs_bmbt_irec	imap;
 	struct xfs_mount	*mp = ip->i_mount;
+	bool			has;
+	int			error;
 
 	/*
-	 * Figure out if there are any blocks beyond the end
-	 * of the file.  If not, then there is nothing to do.
+	 * If there are blocks after the end of file, truncate the file to its
+	 * current size to free them up.
 	 */
-	end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)XFS_ISIZE(ip));
-	last_fsb = XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes);
-	if (last_fsb <= end_fsb)
-		return 0;
-	map_len = last_fsb - end_fsb;
-
-	nimaps = 1;
-	xfs_ilock(ip, XFS_ILOCK_SHARED);
-	error = xfs_bmapi_read(ip, end_fsb, map_len, &imap, &nimaps, 0);
-	xfs_iunlock(ip, XFS_ILOCK_SHARED);
+	error = xfs_has_eofblocks(ip, &has);
+	if (error || !has)
+		return error;
 
 	/*
-	 * If there are blocks after the end of file, truncate the file to its
-	 * current size to free them up.
+	 * Attach the dquots to the inode up front.
 	 */
-	if (!error && (nimaps != 0) &&
-	    (imap.br_startblock != HOLESTARTBLOCK ||
-	     ip->i_delayed_blks)) {
-		/*
-		 * Attach the dquots to the inode up front.
-		 */
-		error = xfs_qm_dqattach(ip, 0);
-		if (error)
-			return error;
+	error = xfs_qm_dqattach(ip, 0);
+	if (error)
+		return error;
 
-		/* wait on dio to ensure i_size has settled */
-		inode_dio_wait(VFS_I(ip));
+	/* wait on dio to ensure i_size has settled */
+	inode_dio_wait(VFS_I(ip));
 
-		error = xfs_trans_alloc(mp, &M_RES(mp)->tr_itruncate, 0, 0, 0,
-				&tp);
-		if (error) {
-			ASSERT(XFS_FORCED_SHUTDOWN(mp));
-			return error;
-		}
+	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_itruncate, 0, 0, 0,
+			&tp);
+	if (error) {
+		ASSERT(XFS_FORCED_SHUTDOWN(mp));
+		return error;
+	}
 
-		xfs_ilock(ip, XFS_ILOCK_EXCL);
-		xfs_trans_ijoin(tp, ip, 0);
+	xfs_ilock(ip, XFS_ILOCK_EXCL);
+	xfs_trans_ijoin(tp, ip, 0);
 
-		/*
-		 * Do not update the on-disk file size.  If we update the
-		 * on-disk file size and then the system crashes before the
-		 * contents of the file are flushed to disk then the files
-		 * may be full of holes (ie NULL files bug).
-		 */
-		error = xfs_itruncate_extents(&tp, ip, XFS_DATA_FORK,
-					      XFS_ISIZE(ip));
-		if (error) {
-			/*
-			 * If we get an error at this point we simply don't
-			 * bother truncating the file.
-			 */
-			xfs_trans_cancel(tp);
-		} else {
-			error = xfs_trans_commit(tp);
-			if (!error)
-				xfs_inode_clear_eofblocks_tag(ip);
-		}
+	/*
+	 * Do not update the on-disk file size.  If we update the
+	 * on-disk file size and then the system crashes before the
+	 * contents of the file are flushed to disk then the files
+	 * may be full of holes (ie NULL files bug).
+	 */
+	error = xfs_itruncate_extents(&tp, ip, XFS_DATA_FORK,
+				      XFS_ISIZE(ip));
+	if (error)
+		goto err_cancel;
 
-		xfs_iunlock(ip, XFS_ILOCK_EXCL);
-	}
+	error = xfs_trans_commit(tp);
+	if (error)
+		goto out_unlock;
+
+	xfs_inode_clear_eofblocks_tag(ip);
+	goto out_unlock;
+
+err_cancel:
+	/*
+	 * If we get an error at this point we simply don't
+	 * bother truncating the file.
+	 */
+	xfs_trans_cancel(tp);
+out_unlock:
+	xfs_iunlock(ip, XFS_ILOCK_EXCL);
 	return error;
 }
 

fs/xfs/xfs_inode.c

@@ -3673,3 +3673,39 @@ xfs_iflush_int(
 corrupt_out:
 	return -EFSCORRUPTED;
 }
+
+/*
+ * Decide if this inode have post-EOF blocks.  The caller is responsible
+ * for knowing / caring about the PREALLOC/APPEND flags.
+ */
+int
+xfs_has_eofblocks(
+	struct xfs_inode	*ip,
+	bool			*has)
+{
+	struct xfs_bmbt_irec	imap;
+	struct xfs_mount	*mp = ip->i_mount;
+	xfs_fileoff_t		end_fsb;
+	xfs_fileoff_t		last_fsb;
+	xfs_filblks_t		map_len;
+	int			nimaps;
+	int			error;
+
+	*has = false;
+	end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)XFS_ISIZE(ip));
+	last_fsb = XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes);
+	if (last_fsb <= end_fsb)
+		return 0;
+	map_len = last_fsb - end_fsb;
+
+	nimaps = 1;
+	xfs_ilock(ip, XFS_ILOCK_SHARED);
+	error = xfs_bmapi_read(ip, end_fsb, map_len, &imap, &nimaps, 0);
+	xfs_iunlock(ip, XFS_ILOCK_SHARED);
+
+	if (error || nimaps == 0)
+		return error;
+
+	*has = imap.br_startblock != HOLESTARTBLOCK || ip->i_delayed_blks;
+	return 0;
+}

fs/xfs/xfs_inode.h

@@ -509,5 +509,6 @@ extern struct kmem_zone	*xfs_inode_zone;
 #define XFS_DEFAULT_COWEXTSZ_HINT 32
 
 bool xfs_inode_verify_forks(struct xfs_inode *ip);
+int xfs_has_eofblocks(struct xfs_inode *ip, bool *has);
 
 #endif	/* __XFS_INODE_H__ */