UBIFS: do not allocate too much

Bulk-read allocates 128KiB or more using kmalloc. The allocation
starts failing often when the memory gets fragmented. UBIFS still
works fine in this case, because it falls-back to standard
(non-optimized) read method, though. This patch teaches bulk-read
to allocate exactly the amount of memory it needs, instead of
allocating 128KiB every time.

This patch is also a preparation to the further fix where we'll
have a pre-allocated bulk-read buffer as well. For example, now
the @bu object is prepared in 'ubifs_bulk_read()', so we could
path either pre-allocated or allocated information to
'ubifs_do_bulk_read()' later. Or teaching 'ubifs_do_bulk_read()'
not to allocate 'bu->buf' if it is already there.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

1 files changed, 6 insertions, 6 deletions

diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
index ea493e6f2652..1d511569c035 100644
--- a/fs/ubifs/super.c
+++ b/fs/ubifs/super.c
@@ -569,16 +569,16 @@ static int init_constants_early(struct ubifs_info *c)
         c->leb_overhead = c->leb_size % UBIFS_MAX_DATA_NODE_SZ;
 
         /* Buffer size for bulk-reads */
-        c->bulk_read_buf_size = UBIFS_MAX_BULK_READ * UBIFS_MAX_DATA_NODE_SZ;
-        if (c->bulk_read_buf_size > c->leb_size)
-                c->bulk_read_buf_size = c->leb_size;
-        if (c->bulk_read_buf_size > UBIFS_KMALLOC_OK) {
+        c->max_bu_buf_len = UBIFS_MAX_BULK_READ * UBIFS_MAX_DATA_NODE_SZ;
+        if (c->max_bu_buf_len > c->leb_size)
+                c->max_bu_buf_len = c->leb_size;
+        if (c->max_bu_buf_len > UBIFS_KMALLOC_OK) {
                 /* Check if we can kmalloc that much */
-                void *try = kmalloc(c->bulk_read_buf_size,
+                void *try = kmalloc(c->max_bu_buf_len,
                                     GFP_KERNEL | __GFP_NOWARN);
                 kfree(try);
                 if (!try)
-                        c->bulk_read_buf_size = UBIFS_KMALLOC_OK;
+                        c->max_bu_buf_len = UBIFS_KMALLOC_OK;
         }
         return 0;
 }