6 files changed, 51 insertions, 29 deletions

diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
index 353e53b892e6..b52ed339727f 100644
--- a/fs/xfs/libxfs/xfs_alloc.c
+++ b/fs/xfs/libxfs/xfs_alloc.c
@@ -82,6 +82,24 @@ xfs_prealloc_blocks(
 }
 
 /*
+ * The number of blocks per AG that we withhold from xfs_mod_fdblocks to
+ * guarantee that we can refill the AGFL prior to allocating space in a nearly
+ * full AG.  Although the the space described by the free space btrees, the
+ * blocks used by the freesp btrees themselves, and the blocks owned by the
+ * AGFL are counted in the ondisk fdblocks, it's a mistake to let the ondisk
+ * free space in the AG drop so low that the free space btrees cannot refill an
+ * empty AGFL up to the minimum level.  Rather than grind through empty AGs
+ * until the fs goes down, we subtract this many AG blocks from the incore
+ * fdblocks to ensure user allocation does not overcommit the space the
+ * filesystem needs for the AGFLs.  The rmap btree uses a per-AG reservation to
+ * withhold space from xfs_mod_fdblocks, so we do not account for that here.
+ */
+#define XFS_ALLOCBT_AGFL_RESERVE	4
+
+/*
+ * Compute the number of blocks that we set aside to guarantee the ability to
+ * refill the AGFL and handle a full bmap btree split.
+ *
  * In order to avoid ENOSPC-related deadlock caused by out-of-order locking of
  * AGF buffer (PV 947395), we place constraints on the relationship among
  * actual allocations for data blocks, freelist blocks, and potential file data
@@ -93,14 +111,14 @@ xfs_prealloc_blocks(
  * extents need to be actually allocated. To get around this, we explicitly set
  * aside a few blocks which will not be reserved in delayed allocation.
  *
- * We need to reserve 4 fsbs _per AG_ for the freelist and 4 more to handle a
- * potential split of the file's bmap btree.
+ * For each AG, we need to reserve enough blocks to replenish a totally empty
+ * AGFL and 4 more to handle a potential split of the file's bmap btree.
  */
 unsigned int
 xfs_alloc_set_aside(
 	struct xfs_mount	*mp)
 {
-	return mp->m_sb.sb_agcount * (XFS_ALLOC_AGFL_RESERVE + 4);
+	return mp->m_sb.sb_agcount * (XFS_ALLOCBT_AGFL_RESERVE + 4);
 }
 
 /*
@@ -124,12 +142,12 @@ xfs_alloc_ag_max_usable(
 	unsigned int		blocks;
 
 	blocks = XFS_BB_TO_FSB(mp, XFS_FSS_TO_BB(mp, 4)); /* ag headers */
-	blocks += XFS_ALLOC_AGFL_RESERVE;
+	blocks += XFS_ALLOCBT_AGFL_RESERVE;
 	blocks += 3;			/* AGF, AGI btree root blocks */
 	if (xfs_has_finobt(mp))
 		blocks++;		/* finobt root block */
 	if (xfs_has_rmapbt(mp))
-		blocks++; 		/* rmap root block */
+		blocks++;		/* rmap root block */
 	if (xfs_has_reflink(mp))
 		blocks++;		/* refcount root block */
 
diff --git a/fs/xfs/libxfs/xfs_alloc.h b/fs/xfs/libxfs/xfs_alloc.h
index 1c14a0b1abea..d4c057b764f9 100644
--- a/fs/xfs/libxfs/xfs_alloc.h
+++ b/fs/xfs/libxfs/xfs_alloc.h
@@ -88,7 +88,6 @@ typedef struct xfs_alloc_arg {
 #define XFS_ALLOC_NOBUSY		(1 << 2)/* Busy extents not allowed */
 
 /* freespace limit calculations */
-#define XFS_ALLOC_AGFL_RESERVE	4
 unsigned int xfs_alloc_set_aside(struct xfs_mount *mp);
 unsigned int xfs_alloc_ag_max_usable(struct xfs_mount *mp);
 
diff --git a/fs/xfs/libxfs/xfs_btree.c b/fs/xfs/libxfs/xfs_btree.c
index f18a875f51c6..c1500b238520 100644
--- a/fs/xfs/libxfs/xfs_btree.c
+++ b/fs/xfs/libxfs/xfs_btree.c
@@ -2818,7 +2818,7 @@ xfs_btree_split_worker(
 	 * in any way.
 	 */
 	if (args->kswapd)
-		new_pflags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD;
+		new_pflags |= PF_MEMALLOC | PF_KSWAPD;
 
 	current_set_flags_nested(&pflags, new_pflags);
 	xfs_trans_set_context(args->cur->bc_tp);
diff --git a/fs/xfs/libxfs/xfs_dir2.c b/fs/xfs/libxfs/xfs_dir2.c
index 50546eadaae2..5f1e4799e8fa 100644
--- a/fs/xfs/libxfs/xfs_dir2.c
+++ b/fs/xfs/libxfs/xfs_dir2.c
@@ -19,7 +19,11 @@
 #include "xfs_error.h"
 #include "xfs_trace.h"
 
-struct xfs_name xfs_name_dotdot = { (unsigned char *)"..", 2, XFS_DIR3_FT_DIR };
+const struct xfs_name xfs_name_dotdot = {
+	.name	= (const unsigned char *)"..",
+	.len	= 2,
+	.type	= XFS_DIR3_FT_DIR,
+};
 
 /*
  * Convert inode mode to directory entry filetype
@@ -54,10 +58,10 @@ xfs_mode_to_ftype(
  */
 xfs_dahash_t
 xfs_ascii_ci_hashname(
-	struct xfs_name	*name)
+	const struct xfs_name	*name)
 {
-	xfs_dahash_t	hash;
-	int		i;
+	xfs_dahash_t		hash;
+	int			i;
 
 	for (i = 0, hash = 0; i < name->len; i++)
 		hash = tolower(name->name[i]) ^ rol32(hash, 7);
@@ -243,7 +247,7 @@ int
 xfs_dir_createname(
 	struct xfs_trans	*tp,
 	struct xfs_inode	*dp,
-	struct xfs_name		*name,
+	const struct xfs_name	*name,
 	xfs_ino_t		inum,		/* new entry inode number */
 	xfs_extlen_t		total)		/* bmap's total block count */
 {
@@ -337,16 +341,16 @@ xfs_dir_cilookup_result(
 
 int
 xfs_dir_lookup(
-	xfs_trans_t	*tp,
-	xfs_inode_t	*dp,
-	struct xfs_name	*name,
-	xfs_ino_t	*inum,		/* out: inode number */
-	struct xfs_name *ci_name)	/* out: actual name if CI match */
+	struct xfs_trans	*tp,
+	struct xfs_inode	*dp,
+	const struct xfs_name	*name,
+	xfs_ino_t		*inum,	  /* out: inode number */
+	struct xfs_name		*ci_name) /* out: actual name if CI match */
 {
-	struct xfs_da_args *args;
-	int		rval;
-	int		v;		/* type-checking value */
-	int		lock_mode;
+	struct xfs_da_args	*args;
+	int			rval;
+	int			v;	  /* type-checking value */
+	int			lock_mode;
 
 	ASSERT(S_ISDIR(VFS_I(dp)->i_mode));
 	XFS_STATS_INC(dp->i_mount, xs_dir_lookup);
@@ -475,7 +479,7 @@ int
 xfs_dir_replace(
 	struct xfs_trans	*tp,
 	struct xfs_inode	*dp,
-	struct xfs_name		*name,		/* name of entry to replace */
+	const struct xfs_name	*name,		/* name of entry to replace */
 	xfs_ino_t		inum,		/* new inode number */
 	xfs_extlen_t		total)		/* bmap's total block count */
 {
@@ -728,7 +732,7 @@ xfs_dir2_namecheck(
 xfs_dahash_t
 xfs_dir2_hashname(
 	struct xfs_mount	*mp,
-	struct xfs_name		*name)
+	const struct xfs_name	*name)
 {
 	if (unlikely(xfs_has_asciici(mp)))
 		return xfs_ascii_ci_hashname(name);
diff --git a/fs/xfs/libxfs/xfs_dir2.h b/fs/xfs/libxfs/xfs_dir2.h
index d03e6098ded9..b6df3c34b26a 100644
--- a/fs/xfs/libxfs/xfs_dir2.h
+++ b/fs/xfs/libxfs/xfs_dir2.h
@@ -21,7 +21,7 @@ struct xfs_dir2_data_unused;
 struct xfs_dir3_icfree_hdr;
 struct xfs_dir3_icleaf_hdr;
 
-extern struct xfs_name	xfs_name_dotdot;
+extern const struct xfs_name	xfs_name_dotdot;
 
 /*
  * Convert inode mode to directory entry filetype
@@ -39,16 +39,16 @@ extern int xfs_dir_isempty(struct xfs_inode *dp);
 extern int xfs_dir_init(struct xfs_trans *tp, struct xfs_inode *dp,
 				struct xfs_inode *pdp);
 extern int xfs_dir_createname(struct xfs_trans *tp, struct xfs_inode *dp,
-				struct xfs_name *name, xfs_ino_t inum,
+				const struct xfs_name *name, xfs_ino_t inum,
 				xfs_extlen_t tot);
 extern int xfs_dir_lookup(struct xfs_trans *tp, struct xfs_inode *dp,
-				struct xfs_name *name, xfs_ino_t *inum,
+				const struct xfs_name *name, xfs_ino_t *inum,
 				struct xfs_name *ci_name);
 extern int xfs_dir_removename(struct xfs_trans *tp, struct xfs_inode *dp,
 				struct xfs_name *name, xfs_ino_t ino,
 				xfs_extlen_t tot);
 extern int xfs_dir_replace(struct xfs_trans *tp, struct xfs_inode *dp,
-				struct xfs_name *name, xfs_ino_t inum,
+				const struct xfs_name *name, xfs_ino_t inum,
 				xfs_extlen_t tot);
 extern int xfs_dir_canenter(struct xfs_trans *tp, struct xfs_inode *dp,
 				struct xfs_name *name);
diff --git a/fs/xfs/libxfs/xfs_dir2_priv.h b/fs/xfs/libxfs/xfs_dir2_priv.h
index 711709a2aa53..7404a9ff1a92 100644
--- a/fs/xfs/libxfs/xfs_dir2_priv.h
+++ b/fs/xfs/libxfs/xfs_dir2_priv.h
@@ -40,7 +40,7 @@ struct xfs_dir3_icfree_hdr {
 };
 
 /* xfs_dir2.c */
-xfs_dahash_t xfs_ascii_ci_hashname(struct xfs_name *name);
+xfs_dahash_t xfs_ascii_ci_hashname(const struct xfs_name *name);
 enum xfs_dacmp xfs_ascii_ci_compname(struct xfs_da_args *args,
 		const unsigned char *name, int len);
 extern int xfs_dir2_grow_inode(struct xfs_da_args *args, int space,
@@ -201,7 +201,8 @@ xfs_dir2_data_entsize(
 	return round_up(len, XFS_DIR2_DATA_ALIGN);
 }
 
-xfs_dahash_t xfs_dir2_hashname(struct xfs_mount *mp, struct xfs_name *name);
+xfs_dahash_t xfs_dir2_hashname(struct xfs_mount *mp,
+		const struct xfs_name *name);
 enum xfs_dacmp xfs_dir2_compname(struct xfs_da_args *args,
 		const unsigned char *name, int len);