btrfs: use kvzalloc to allocate btrfs_fs_info

The srcu_struct in btrfs_fs_info scales in size with NR_CPUS.  On
kernels built with NR_CPUS=8192, this can result in kmalloc failures
that prevent mounting.

There is work in progress to try to resolve this for every user of
srcu_struct but using kvzalloc will work around the failures until
that is complete.

As an example with NR_CPUS=512 on x86_64: the overall size of
subvol_srcu is 3460 bytes, fs_info is 6496.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

2 files changed, 2 insertions, 2 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 1a462ab85c49..0f521ba5f2f9 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -2974,7 +2974,7 @@ static inline void free_fs_info(struct btrfs_fs_info *fs_info)
         kfree(fs_info->super_copy);
         kfree(fs_info->super_for_commit);
         security_free_mnt_opts(&fs_info->security_opts);
-        kfree(fs_info);
+        kvfree(fs_info);
 }
 
 /* tree mod log functions from ctree.c */
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 6e71a2a78363..4b817947e00f 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -1545,7 +1545,7 @@ static struct dentry *btrfs_mount_root(struct file_system_type *fs_type,
          * it for searching for existing supers, so this lets us do that and
          * then open_ctree will properly initialize everything later.
          */
-        fs_info = kzalloc(sizeof(struct btrfs_fs_info), GFP_KERNEL);
+        fs_info = kvzalloc(sizeof(struct btrfs_fs_info), GFP_KERNEL);
         if (!fs_info) {
                 error = -ENOMEM;
                 goto error_sec_opts;