Commit 9cb20f94 authored by Ira Weiny's avatar Ira Weiny Committed by Theodore Ts'o
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fs/ext4: Make DAX mount option a tri-state 



We add 'always', 'never', and 'inode' (default).  '-o dax' continues to
operate the same which is equivalent to 'always'.  This new
functionality is limited to ext4 only.

Specifically we introduce a 2nd DAX mount flag EXT4_MOUNT2_DAX_NEVER and set
it and EXT4_MOUNT_DAX_ALWAYS appropriately for the mode.

We also force EXT4_MOUNT2_DAX_NEVER if !CONFIG_FS_DAX.

Finally, EXT4_MOUNT2_DAX_INODE is used solely to detect if the user
specified that option for printing.

Reviewed-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarIra Weiny <ira.weiny@intel.com>

Link: https://lore.kernel.org/r/20200528150003.828793-7-ira.weiny@intel.com


Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent 043546e4

fs/ext4/ext4.h

+2 −0
Original line number Diff line number Diff line
@@ -1168,6 +1168,8 @@ struct ext4_inode_info { 
						      blocks */

#define EXT4_MOUNT2_HURD_COMPAT		0x00000004 /* Support HURD-castrated

						      file systems */

#define EXT4_MOUNT2_DAX_NEVER		0x00000008 /* Do not allow Direct Access */

#define EXT4_MOUNT2_DAX_INODE		0x00000010 /* For printing options only */



#define EXT4_MOUNT2_EXPLICIT_JOURNAL_CHECKSUM	0x00000008 /* User explicitly

						specified journal checksum */

fs/ext4/inode.c

+2 −0
Original line number Diff line number Diff line
@@ -4402,6 +4402,8 @@ static bool ext4_should_enable_dax(struct inode *inode) 
{

	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);



	if (test_opt2(inode->i_sb, DAX_NEVER))

		return false;

	if (!S_ISREG(inode->i_mode))

		return false;

	if (ext4_should_journal_data(inode))

fs/ext4/super.c

+57 −10
Original line number Diff line number Diff line
@@ -1512,7 +1512,8 @@ enum { 
	Opt_usrjquota, Opt_grpjquota, Opt_offusrjquota, Opt_offgrpjquota,

	Opt_jqfmt_vfsold, Opt_jqfmt_vfsv0, Opt_jqfmt_vfsv1, Opt_quota,

	Opt_noquota, Opt_barrier, Opt_nobarrier, Opt_err,

	Opt_usrquota, Opt_grpquota, Opt_prjquota, Opt_i_version, Opt_dax,

	Opt_usrquota, Opt_grpquota, Opt_prjquota, Opt_i_version,

	Opt_dax, Opt_dax_always, Opt_dax_inode, Opt_dax_never,

	Opt_stripe, Opt_delalloc, Opt_nodelalloc, Opt_warn_on_error,

	Opt_nowarn_on_error, Opt_mblk_io_submit,

	Opt_lazytime, Opt_nolazytime, Opt_debug_want_extra_isize,
@@ -1579,6 +1580,9 @@ static const match_table_t tokens = { 
	{Opt_nobarrier, "nobarrier"},

	{Opt_i_version, "i_version"},

	{Opt_dax, "dax"},

	{Opt_dax_always, "dax=always"},

	{Opt_dax_inode, "dax=inode"},

	{Opt_dax_never, "dax=never"},

	{Opt_stripe, "stripe=%u"},

	{Opt_delalloc, "delalloc"},

	{Opt_warn_on_error, "warn_on_error"},
@@ -1726,6 +1730,7 @@ static int clear_qf_name(struct super_block *sb, int qtype) 
#define MOPT_NO_EXT3	0x0200

#define MOPT_EXT4_ONLY	(MOPT_NO_EXT2 | MOPT_NO_EXT3)

#define MOPT_STRING	0x0400

#define MOPT_SKIP	0x0800



static const struct mount_opts {

	int	token;
@@ -1775,7 +1780,13 @@ static const struct mount_opts { 
	{Opt_min_batch_time, 0, MOPT_GTE0},

	{Opt_inode_readahead_blks, 0, MOPT_GTE0},

	{Opt_init_itable, 0, MOPT_GTE0},

	{Opt_dax, EXT4_MOUNT_DAX_ALWAYS, MOPT_SET},

	{Opt_dax, EXT4_MOUNT_DAX_ALWAYS, MOPT_SET | MOPT_SKIP},

	{Opt_dax_always, EXT4_MOUNT_DAX_ALWAYS,

		MOPT_EXT4_ONLY | MOPT_SET | MOPT_SKIP},

	{Opt_dax_inode, EXT4_MOUNT2_DAX_INODE,

		MOPT_EXT4_ONLY | MOPT_SET | MOPT_SKIP},

	{Opt_dax_never, EXT4_MOUNT2_DAX_NEVER,

		MOPT_EXT4_ONLY | MOPT_SET | MOPT_SKIP},

	{Opt_stripe, 0, MOPT_GTE0},

	{Opt_resuid, 0, MOPT_GTE0},

	{Opt_resgid, 0, MOPT_GTE0},
@@ -2084,13 +2095,32 @@ static int handle_mount_opt(struct super_block *sb, char *opt, int token, 
		}

		sbi->s_jquota_fmt = m->mount_opt;

#endif

	} else if (token == Opt_dax) {

	} else if (token == Opt_dax || token == Opt_dax_always ||

		   token == Opt_dax_inode || token == Opt_dax_never) {

#ifdef CONFIG_FS_DAX

		switch (token) {

		case Opt_dax:

		case Opt_dax_always:

			ext4_msg(sb, KERN_WARNING,

				"DAX enabled. Warning: EXPERIMENTAL, use at your own risk");

		sbi->s_mount_opt |= m->mount_opt;

			sbi->s_mount_opt |= EXT4_MOUNT_DAX_ALWAYS;

			sbi->s_mount_opt2 &= ~EXT4_MOUNT2_DAX_NEVER;

			break;

		case Opt_dax_never:

			sbi->s_mount_opt2 |= EXT4_MOUNT2_DAX_NEVER;

			sbi->s_mount_opt &= ~EXT4_MOUNT_DAX_ALWAYS;

			break;

		case Opt_dax_inode:

			sbi->s_mount_opt &= ~EXT4_MOUNT_DAX_ALWAYS;

			sbi->s_mount_opt2 &= ~EXT4_MOUNT2_DAX_NEVER;

			/* Strictly for printing options */

			sbi->s_mount_opt2 |= EXT4_MOUNT2_DAX_INODE;

			break;

		}

#else

		ext4_msg(sb, KERN_INFO, "dax option not supported");

		sbi->s_mount_opt2 |= EXT4_MOUNT2_DAX_NEVER;

		sbi->s_mount_opt &= ~EXT4_MOUNT_DAX_ALWAYS;

		return -1;

#endif

	} else if (token == Opt_data_err_abort) {
@@ -2254,7 +2284,7 @@ static int _ext4_show_options(struct seq_file *seq, struct super_block *sb, 
	for (m = ext4_mount_opts; m->token != Opt_err; m++) {

		int want_set = m->flags & MOPT_SET;

		if (((m->flags & (MOPT_SET|MOPT_CLEAR)) == 0) ||

		    (m->flags & MOPT_CLEAR_ERR))

		    (m->flags & MOPT_CLEAR_ERR) || m->flags & MOPT_SKIP)

			continue;

		if (!nodefs && !(m->mount_opt & (sbi->s_mount_opt ^ def_mount_opt)))

			continue; /* skip if same as the default */
@@ -2314,6 +2344,17 @@ static int _ext4_show_options(struct seq_file *seq, struct super_block *sb, 
	if (DUMMY_ENCRYPTION_ENABLED(sbi))

		SEQ_OPTS_PUTS("test_dummy_encryption");



	if (test_opt(sb, DAX_ALWAYS)) {

		if (IS_EXT2_SB(sb))

			SEQ_OPTS_PUTS("dax");

		else

			SEQ_OPTS_PUTS("dax=always");

	} else if (test_opt2(sb, DAX_NEVER)) {

		SEQ_OPTS_PUTS("dax=never");

	} else if (test_opt2(sb, DAX_INODE)) {

		SEQ_OPTS_PUTS("dax=inode");

	}



	ext4_show_quota_options(seq, sb);

	return 0;

}
@@ -5436,10 +5477,16 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data) 
		goto restore_opts;

	}



	if ((sbi->s_mount_opt ^ old_opts.s_mount_opt) & EXT4_MOUNT_DAX_ALWAYS) {

	if ((sbi->s_mount_opt ^ old_opts.s_mount_opt) & EXT4_MOUNT_DAX_ALWAYS ||

	    (sbi->s_mount_opt2 ^ old_opts.s_mount_opt2) & EXT4_MOUNT2_DAX_NEVER ||

	    (sbi->s_mount_opt2 ^ old_opts.s_mount_opt2) & EXT4_MOUNT2_DAX_INODE) {

		ext4_msg(sb, KERN_WARNING, "warning: refusing change of "

			"dax flag with busy inodes while remounting");

		sbi->s_mount_opt ^= EXT4_MOUNT_DAX_ALWAYS;

			"dax mount option with busy inodes while remounting");

		sbi->s_mount_opt &= ~EXT4_MOUNT_DAX_ALWAYS;

		sbi->s_mount_opt |= old_opts.s_mount_opt & EXT4_MOUNT_DAX_ALWAYS;

		sbi->s_mount_opt2 &= ~(EXT4_MOUNT2_DAX_NEVER | EXT4_MOUNT2_DAX_INODE);

		sbi->s_mount_opt2 |= old_opts.s_mount_opt2 &

				     (EXT4_MOUNT2_DAX_NEVER | EXT4_MOUNT2_DAX_INODE);

	}



	if (sbi->s_mount_flags & EXT4_MF_FS_ABORTED)

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