linux-kernel - [RFC PATCH 06/21] ubifs: Avoid allocating buffer space unnecessarily

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Message-Id: <20230718125847.3869700-7-ardb@kernel.org>
Date:   Tue, 18 Jul 2023 14:58:32 +0200
From:   Ard Biesheuvel <ardb@...nel.org>
To:     linux-crypto@...r.kernel.org
Cc:     Ard Biesheuvel <ardb@...nel.org>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Eric Biggers <ebiggers@...nel.org>,
        Kees Cook <keescook@...omium.org>,
        Haren Myneni <haren@...ibm.com>,
        Nick Terrell <terrelln@...com>,
        Minchan Kim <minchan@...nel.org>,
        Sergey Senozhatsky <senozhatsky@...omium.org>,
        Jens Axboe <axboe@...nel.dk>,
        Giovanni Cabiddu <giovanni.cabiddu@...el.com>,
        Richard Weinberger <richard@....at>,
        David Ahern <dsahern@...nel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Steffen Klassert <steffen.klassert@...unet.com>,
        linux-kernel@...r.kernel.org, linux-block@...r.kernel.org,
        qat-linux@...el.com, linuxppc-dev@...ts.ozlabs.org,
        linux-mtd@...ts.infradead.org, netdev@...r.kernel.org
Subject: [RFC PATCH 06/21] ubifs: Avoid allocating buffer space unnecessarily

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 <ardb@...nel.org>
---
 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