ext4: add debug_want_extra_isize mount option

In order to test the inode extra isize expansion code, it is useful to
be able to easily create file systems that have inodes with extra
isize values smaller than the current desired value.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 9d15a6293124d673696b609bf368c16d737848dc..829e4a7b59e484d9704d3b378f23862f16223215 100644 (file)
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1284,7 +1284,7 @@ enum {
        Opt_noquota, Opt_barrier, Opt_nobarrier, Opt_err,
        Opt_usrquota, Opt_grpquota, Opt_prjquota, Opt_i_version, Opt_dax,
        Opt_stripe, Opt_delalloc, Opt_nodelalloc, Opt_mblk_io_submit,
-       Opt_lazytime, Opt_nolazytime,
+       Opt_lazytime, Opt_nolazytime, Opt_debug_want_extra_isize,
        Opt_nomblk_io_submit, Opt_block_validity, Opt_noblock_validity,
        Opt_inode_readahead_blks, Opt_journal_ioprio,
        Opt_dioread_nolock, Opt_dioread_lock,
@@ -1352,6 +1352,7 @@ static const match_table_t tokens = {
        {Opt_delalloc, "delalloc"},
        {Opt_lazytime, "lazytime"},
        {Opt_nolazytime, "nolazytime"},
+       {Opt_debug_want_extra_isize, "debug_want_extra_isize=%u"},
        {Opt_nodelalloc, "nodelalloc"},
        {Opt_removed, "mblk_io_submit"},
        {Opt_removed, "nomblk_io_submit"},
@@ -1557,6 +1558,7 @@ static const struct mount_opts {
 #endif
        {Opt_nouid32, EXT4_MOUNT_NO_UID32, MOPT_SET},
        {Opt_debug, EXT4_MOUNT_DEBUG, MOPT_SET},
+       {Opt_debug_want_extra_isize, 0, MOPT_GTE0},
        {Opt_quota, EXT4_MOUNT_QUOTA | EXT4_MOUNT_USRQUOTA, MOPT_SET | MOPT_Q},
        {Opt_usrquota, EXT4_MOUNT_QUOTA | EXT4_MOUNT_USRQUOTA,
                                                        MOPT_SET | MOPT_Q},
@@ -1670,6 +1672,8 @@ static int handle_mount_opt(struct super_block *sb, char *opt, int token,
                if (arg == 0)
                        arg = JBD2_DEFAULT_MAX_COMMIT_AGE;
                sbi->s_commit_interval = HZ * arg;
+       } else if (token == Opt_debug_want_extra_isize) {
+               sbi->s_want_extra_isize = arg;
        } else if (token == Opt_max_batch_time) {
                sbi->s_max_batch_time = arg;
        } else if (token == Opt_min_batch_time) {
@@ -4081,7 +4085,8 @@ no_journal:
                sb->s_flags |= MS_RDONLY;
 
        /* determine the minimum size of new large inodes, if present */
-       if (sbi->s_inode_size > EXT4_GOOD_OLD_INODE_SIZE) {
+       if (sbi->s_inode_size > EXT4_GOOD_OLD_INODE_SIZE &&
+           sbi->s_want_extra_isize == 0) {
                sbi->s_want_extra_isize = sizeof(struct ext4_inode) -
                                                     EXT4_GOOD_OLD_INODE_SIZE;
                if (ext4_has_feature_extra_isize(sb)) {