ext4: teach the inode allocator to use a goal inode number

Enhance the inode allocator to take a goal inode number as a
paremeter; if it is specified, it takes precedence over Orlov or
parent directory inode allocation algorithms.

The extents migration function uses the goal inode number so that the
extent trees allocated the migration function use the correct flex_bg.
In the future, the goal inode functionality will also be used to
allocate an adjacent inode for the extended attributes.

Also, for testing purposes the goal inode number can be specified via
/sys/fs/{dev}/inode_goal.  This can be useful for testing inode
allocation beyond 2^32 blocks on very large filesystems.

Signed-off-by: Andreas Dilger <adilger@sun.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 2 insertions, 1 deletions

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index d035cf149e0e..746cdcba969d 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -863,6 +863,7 @@ struct ext4_sb_info {
         int s_inode_size;
         int s_first_ino;
         unsigned int s_inode_readahead_blks;
+        unsigned int s_inode_goal;
         spinlock_t s_next_gen_lock;
         u32 s_next_generation;
         u32 s_hash_seed[4];
@@ -1316,7 +1317,7 @@ extern int ext4fs_dirhash(const char *name, int len, struct
 
 /* ialloc.c */
 extern struct inode *ext4_new_inode(handle_t *, struct inode *, int,
-                                    const struct qstr *qstr);
+                                    const struct qstr *qstr, __u32 goal);
 extern void ext4_free_inode(handle_t *, struct inode *);
 extern struct inode * ext4_orphan_get(struct super_block *, unsigned long);
 extern unsigned long ext4_count_free_inodes(struct super_block *);