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>

1 files changed, 48 insertions, 9 deletions

diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
index 1d511569c035..d80b2aef42b6 100644
--- a/fs/ubifs/super.c
+++ b/fs/ubifs/super.c
@@ -572,14 +572,6 @@ static int init_constants_early(struct ubifs_info *c)
         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->max_bu_buf_len,
-                                    GFP_KERNEL | __GFP_NOWARN);
-                kfree(try);
-                if (!try)
-                        c->max_bu_buf_len = UBIFS_KMALLOC_OK;
-        }
         return 0;
 }
 
@@ -999,6 +991,34 @@ static void destroy_journal(struct ubifs_info *c)
 }
 
 /**
+ * bu_init - initialize bulk-read information.
+ * @c: UBIFS file-system description object
+ */
+static void bu_init(struct ubifs_info *c)
+{
+        ubifs_assert(c->bulk_read == 1);
+
+        if (c->bu.buf)
+                return; /* Already initialized */
+
+again:
+        c->bu.buf = kmalloc(c->max_bu_buf_len, GFP_KERNEL | __GFP_NOWARN);
+        if (!c->bu.buf) {
+                if (c->max_bu_buf_len > UBIFS_KMALLOC_OK) {
+                        c->max_bu_buf_len = UBIFS_KMALLOC_OK;
+                        goto again;
+                }
+
+                /* Just disable bulk-read */
+                ubifs_warn("Cannot allocate %d bytes of memory for bulk-read, "
+                           "disabling it", c->max_bu_buf_len);
+                c->mount_opts.bulk_read = 1;
+                c->bulk_read = 0;
+                return;
+        }
+}
+
+/**
  * mount_ubifs - mount UBIFS file-system.
  * @c: UBIFS file-system description object
  *
@@ -1066,6 +1086,13 @@ static int mount_ubifs(struct ubifs_info *c)
                         goto out_free;
         }
 
+        if (c->bulk_read == 1)
+                bu_init(c);
+
+        /*
+         * We have to check all CRCs, even for data nodes, when we mount the FS
+         * (specifically, when we are replaying).
+         */
         c->always_chk_crc = 1;
 
         err = ubifs_read_superblock(c);
@@ -1296,6 +1323,7 @@ out_cbuf:
 out_dereg:
         dbg_failure_mode_deregistration(c);
 out_free:
+        kfree(c->bu.buf);
         vfree(c->ileb_buf);
         vfree(c->sbuf);
         kfree(c->bottom_up_buf);
@@ -1332,10 +1360,11 @@ static void ubifs_umount(struct ubifs_info *c)
         kfree(c->cbuf);
         kfree(c->rcvrd_mst_node);
         kfree(c->mst_node);
+        kfree(c->bu.buf);
+        vfree(c->ileb_buf);
         vfree(c->sbuf);
         kfree(c->bottom_up_buf);
         UBIFS_DBG(vfree(c->dbg_buf));
-        vfree(c->ileb_buf);
         dbg_failure_mode_deregistration(c);
 }
 
@@ -1633,6 +1662,7 @@ static int ubifs_remount_fs(struct super_block *sb, int *flags, char *data)
                 ubifs_err("invalid or unknown remount parameter");
                 return err;
         }
+
         if ((sb->s_flags & MS_RDONLY) && !(*flags & MS_RDONLY)) {
                 err = ubifs_remount_rw(c);
                 if (err)
@@ -1640,6 +1670,14 @@ static int ubifs_remount_fs(struct super_block *sb, int *flags, char *data)
         } else if (!(sb->s_flags & MS_RDONLY) && (*flags & MS_RDONLY))
                 ubifs_remount_ro(c);
 
+        if (c->bulk_read == 1)
+                bu_init(c);
+        else {
+                dbg_gen("disable bulk-read");
+                kfree(c->bu.buf);
+                c->bu.buf = NULL;
+        }
+
         return 0;
 }
 
@@ -1730,6 +1768,7 @@ static int ubifs_fill_super(struct super_block *sb, void *data, int silent)
         mutex_init(&c->log_mutex);
         mutex_init(&c->mst_mutex);
         mutex_init(&c->umount_mutex);
+        mutex_init(&c->bu_mutex);
         init_waitqueue_head(&c->cmt_wq);
         c->buds = RB_ROOT;
         c->old_idx = RB_ROOT;