[PATCH 03/21] xfs: refactor part of xfs_free_eofblocks

["Darrick J. Wong" <darrick.wong@oracle.com>]

From: Darrick J. Wong <darrick.wong@oracle.com>

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 repair freeze patch requires us to defer iput of an inode if
disposing of that inode would have to start another transaction to
unwind incore state.  No functionality changes.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/xfs/xfs_bmap_util.c |  101 ++++++++++++++++++++----------------------------
 fs/xfs/xfs_inode.c     |   32 +++++++++++++++
 fs/xfs/xfs_inode.h     |    1 
 3 files changed, 75 insertions(+), 59 deletions(-)


diff --git a/fs/xfs/xfs_bmap_util.c b/fs/xfs/xfs_bmap_util.c
index c94d376e4152..0f38acbb200f 100644
--- a/fs/xfs/xfs_bmap_util.c
+++ b/fs/xfs/xfs_bmap_util.c
@@ -805,78 +805,61 @@ 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;
+	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)
+	if (!xfs_inode_has_posteof_blocks(ip))
 		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 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);
-		if (error)
-			return error;
+	error = xfs_qm_dqattach(ip);
+	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_flags(&tp, ip, XFS_DATA_FORK,
-					XFS_ISIZE(ip), XFS_BMAPI_NODISCARD);
-		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_flags(&tp, ip, XFS_DATA_FORK,
+				XFS_ISIZE(ip), XFS_BMAPI_NODISCARD);
+	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;
 }
 
diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index e6859dfc29af..368ac0528727 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -3708,3 +3708,35 @@ xfs_inode_has_cow_blocks(
 	}
 	return false;
 }
+
+/*
+ * Decide if this inode have post-EOF blocks.  The caller is responsible
+ * for knowing / caring about the PREALLOC/APPEND flags.
+ */
+bool
+xfs_inode_has_posteof_blocks(
+	struct xfs_inode	*ip)
+{
+	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;
+
+	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 false;
+	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);
+
+	return !error && (nimaps != 0) &&
+	       (imap.br_startblock != HOLESTARTBLOCK ||
+	        ip->i_delayed_blks);
+}
diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
index 735d0788bfdb..a041fffa1b33 100644
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -504,5 +504,6 @@ extern struct kmem_zone	*xfs_inode_zone;
 
 bool xfs_inode_verify_forks(struct xfs_inode *ip);
 bool xfs_inode_has_cow_blocks(struct xfs_inode *ip);
+bool xfs_inode_has_posteof_blocks(struct xfs_inode *ip);
 
 #endif	/* __XFS_INODE_H__ */