[PATCH mmotm 1/5] nilfs2: fix problems of memory allocation in ioctl

[Ryusuke Konishi]

The current memory copy function of nilfs2 ioctl has following
problems:

(1) It tries to allocate 128KB size of memory even for small objects.

(2) Though the function repeatedly tries large memory allocations
    while reducing the size, GFP_NOWAIT flag is not specified.
    This increases the possibility of system memory shortage.

(3) During the retries of (2), verbose warnings are printed
    because _GFP_NOWARN flag is not used for the kmalloc calls.

This will fix these problems.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxxxxxx>
---
 fs/nilfs2/ioctl.c |   17 ++++++++++++-----
 1 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/fs/nilfs2/ioctl.c b/fs/nilfs2/ioctl.c
index 35ba60e..5ba6e4e 100644
--- a/fs/nilfs2/ioctl.c
+++ b/fs/nilfs2/ioctl.c
@@ -51,13 +51,20 @@ static int nilfs_ioctl_wrap_copy(struct the_nilfs *nilfs,
 	if (argv->v_nmembs == 0)
 		return 0;
 
-	for (ksize = KMALLOC_SIZE_MAX; ksize >= KMALLOC_SIZE_MIN; ksize /= 2) {
-		buf = kmalloc(ksize, GFP_NOFS);
-		if (buf != NULL)
-			break;
+	ksize = min_t(unsigned long, argv->v_nmembs * argv->v_size,
+		      KMALLOC_SIZE_MAX);
+	while (ksize >= KMALLOC_SIZE_MIN) {
+		buf = kmalloc(ksize, GFP_NOWAIT | __GFP_NOWARN);
+		if (buf)
+			goto allocated;
+		ksize >>= 1;
 	}
-	if (ksize < KMALLOC_SIZE_MIN)
+	ksize = max_t(size_t, ksize, argv->v_size);
+	buf = kmalloc(ksize, GFP_NOFS);
+	if (unlikely(!buf))
 		return -ENOMEM;
+
+ allocated:
 	maxmembs = ksize / argv->v_size;
 
 	ret = 0;
-- 
1.5.6.5

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/