UBIFS: pre-allocate bulk-read buffer
To avoid memory allocation failure during bulk-read, pre-allocate
a bulk-read buffer, so that if there is only one bulk-reader at
a time, it would just use the pre-allocated buffer and would not
do any memory allocation. However, if there are more than 1 bulk-
reader, then only one reader would use the pre-allocated buffer,
while the other reader would allocate the buffer for itself.
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
diff --git a/fs/ubifs/file.c b/fs/ubifs/file.c
index 0c5c27d..2624411 100644
--- a/fs/ubifs/file.c
+++ b/fs/ubifs/file.c
@@ -811,15 +811,15 @@
struct ubifs_inode *ui = ubifs_inode(inode);
pgoff_t index = page->index, last_page_read = ui->last_page_read;
struct bu_info *bu;
- int err = 0;
+ int err = 0, allocated = 0;
ui->last_page_read = index;
if (!c->bulk_read)
return 0;
/*
- * Bulk-read is protected by ui_mutex, but it is an optimization, so
- * don't bother if we cannot lock the mutex.
+ * Bulk-read is protected by @ui->ui_mutex, but it is an optimization,
+ * so don't bother if we cannot lock the mutex.
*/
if (!mutex_trylock(&ui->ui_mutex))
return 0;
@@ -840,17 +840,30 @@
ui->bulk_read = 1;
}
- bu = kmalloc(sizeof(struct bu_info), GFP_NOFS | __GFP_NOWARN);
- if (!bu)
- return 0;
+ /*
+ * If possible, try to use pre-allocated bulk-read information, which
+ * is protected by @c->bu_mutex.
+ */
+ if (mutex_trylock(&c->bu_mutex))
+ bu = &c->bu;
+ else {
+ bu = kmalloc(sizeof(struct bu_info), GFP_NOFS | __GFP_NOWARN);
+ if (!bu)
+ goto out_unlock;
- bu->buf = NULL;
+ bu->buf = NULL;
+ allocated = 1;
+ }
+
bu->buf_len = c->max_bu_buf_len;
data_key_init(c, &bu->key, inode->i_ino,
page->index << UBIFS_BLOCKS_PER_PAGE_SHIFT);
-
err = ubifs_do_bulk_read(c, bu, page);
- kfree(bu);
+
+ if (!allocated)
+ mutex_unlock(&c->bu_mutex);
+ else
+ kfree(bu);
out_unlock:
mutex_unlock(&ui->ui_mutex);