[PATCH 1/2] xfs: standardize GFP flags usage in online scrub

["Darrick J. Wong" <djwong@xxxxxxxxxx>]

From: Darrick J. Wong <djwong@xxxxxxxxxx>

Memory allocation usage is the same throughout online fsck -- we want
kernel memory, we have to be able to back out if we can't allocate
memory, and we don't want to spray dmesg with memory allocation failure
reports.  Standardize the GFP flag usage and document these requirements.

Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx>
---
 fs/xfs/scrub/agheader.c |    2 +-
 fs/xfs/scrub/attr.c     |    9 ++++-----
 fs/xfs/scrub/scrub.h    |    9 +++++++++
 fs/xfs/scrub/symlink.c  |    2 +-
 4 files changed, 15 insertions(+), 7 deletions(-)


diff --git a/fs/xfs/scrub/agheader.c b/fs/xfs/scrub/agheader.c
index af284baa6f4c..4dd52b15f09c 100644
--- a/fs/xfs/scrub/agheader.c
+++ b/fs/xfs/scrub/agheader.c
@@ -737,7 +737,7 @@ xchk_agfl(
 		goto out;
 	}
 	sai.entries = kvcalloc(sai.agflcount, sizeof(xfs_agblock_t),
-			GFP_KERNEL | __GFP_RETRY_MAYFAIL);
+			       XCHK_GFP_FLAGS);
 	if (!sai.entries) {
 		error = -ENOMEM;
 		goto out;
diff --git a/fs/xfs/scrub/attr.c b/fs/xfs/scrub/attr.c
index b6f0c9f3f124..11b2593a2be7 100644
--- a/fs/xfs/scrub/attr.c
+++ b/fs/xfs/scrub/attr.c
@@ -79,7 +79,8 @@ xchk_setup_xattr(
 	 * without the inode lock held, which means we can sleep.
 	 */
 	if (sc->flags & XCHK_TRY_HARDER) {
-		error = xchk_setup_xattr_buf(sc, XATTR_SIZE_MAX, GFP_KERNEL);
+		error = xchk_setup_xattr_buf(sc, XATTR_SIZE_MAX,
+				XCHK_GFP_FLAGS);
 		if (error)
 			return error;
 	}
@@ -138,8 +139,7 @@ xchk_xattr_listent(
 	 * doesn't work, we overload the seen_enough variable to convey
 	 * the error message back to the main scrub function.
 	 */
-	error = xchk_setup_xattr_buf(sx->sc, valuelen,
-			GFP_KERNEL | __GFP_RETRY_MAYFAIL);
+	error = xchk_setup_xattr_buf(sx->sc, valuelen, XCHK_GFP_FLAGS);
 	if (error == -ENOMEM)
 		error = -EDEADLOCK;
 	if (error) {
@@ -324,8 +324,7 @@ xchk_xattr_block(
 		return 0;
 
 	/* Allocate memory for block usage checking. */
-	error = xchk_setup_xattr_buf(ds->sc, 0,
-			GFP_KERNEL | __GFP_RETRY_MAYFAIL);
+	error = xchk_setup_xattr_buf(ds->sc, 0, XCHK_GFP_FLAGS);
 	if (error == -ENOMEM)
 		return -EDEADLOCK;
 	if (error)
diff --git a/fs/xfs/scrub/scrub.h b/fs/xfs/scrub/scrub.h
index 151567f88366..a0f097b8acb0 100644
--- a/fs/xfs/scrub/scrub.h
+++ b/fs/xfs/scrub/scrub.h
@@ -8,6 +8,15 @@
 
 struct xfs_scrub;
 
+/*
+ * Standard flags for allocating memory within scrub.  NOFS context is
+ * configured by the process allocation scope.  Scrub and repair must be able
+ * to back out gracefully if there isn't enough memory.  Force-cast to avoid
+ * complaints from static checkers.
+ */
+#define XCHK_GFP_FLAGS	((__force gfp_t)(GFP_KERNEL | __GFP_NOWARN | \
+					 __GFP_RETRY_MAYFAIL))
+
 /* Type info and names for the scrub types. */
 enum xchk_type {
 	ST_NONE = 1,	/* disabled */
diff --git a/fs/xfs/scrub/symlink.c b/fs/xfs/scrub/symlink.c
index 75311f8daeeb..c1c99ffe7408 100644
--- a/fs/xfs/scrub/symlink.c
+++ b/fs/xfs/scrub/symlink.c
@@ -21,7 +21,7 @@ xchk_setup_symlink(
 	struct xfs_scrub	*sc)
 {
 	/* Allocate the buffer without the inode lock held. */
-	sc->buf = kvzalloc(XFS_SYMLINK_MAXLEN + 1, GFP_KERNEL);
+	sc->buf = kvzalloc(XFS_SYMLINK_MAXLEN + 1, XCHK_GFP_FLAGS);
 	if (!sc->buf)
 		return -ENOMEM;