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>

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 1a462ab85c49888a3962b026a74ede8c47182fc1..0f521ba5f2f9672ebdd1b0a4821ca0c000d716f4 100644 (file)
--- 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 6e71a2a783630ac15d2d910fd0613347c4a260ac..4b817947e00f39e327a244f67bbde7ebf2d6b7e0 100644 (file)
--- 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;