Subject: [RFC PATCH 06/21] ubifs: Avoid allocating buffer space unnecessarily

From: Ard Biesheuvel <[email-masked]>
Date: Tue, 18 Jul 2023 14:58:32 +0200

The recompression scratch buffer is only used when the data node is
compressed, and there is no need to allocate it otherwise. So move the
allocation into the branch of the if() that actually makes use of it.

Signed-off-by: Ard Biesheuvel <[email-masked]>
---
 fs/ubifs/journal.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/fs/ubifs/journal.c b/fs/ubifs/journal.c
index 4e5961878f336033..5ce618f82aed201b 100644
--- a/fs/ubifs/journal.c
+++ b/fs/ubifs/journal.c
@@ -1485,16 +1485,9 @@ static int truncate_data_node(const struct ubifs_info *c, const struct inode *in
 			      unsigned int block, struct ubifs_data_node *dn,
 			      int *new_len, int dn_size)
 {
-	void *buf;
+	void *buf = NULL;
 	int err, dlen, compr_type, out_len, data_size;
 
-	out_len = le32_to_cpu(dn->size);
-	buf = kmalloc_array(out_len, WORST_COMPR_FACTOR, GFP_NOFS);
-	if (!buf)
-		return -ENOMEM;
-
-	out_len *= WORST_COMPR_FACTOR;
-
 	dlen = le32_to_cpu(dn->ch.len) - UBIFS_DATA_NODE_SZ;
 	data_size = dn_size - UBIFS_DATA_NODE_SZ;
 	compr_type = le16_to_cpu(dn->compr_type);
@@ -1508,6 +1501,13 @@ static int truncate_data_node(const struct ubifs_info *c, const struct inode *in
 	if (compr_type == UBIFS_COMPR_NONE) {
 		out_len = *new_len;
 	} else {
+		out_len = le32_to_cpu(dn->size);
+		buf = kmalloc_array(out_len, WORST_COMPR_FACTOR, GFP_NOFS);
+		if (!buf)
+			return -ENOMEM;
+
+		out_len *= WORST_COMPR_FACTOR;
+
 		err = ubifs_decompress(c, &dn->data, dlen, buf, &out_len, compr_type);
 		if (err)
 			goto out;
-- 
2.39.2