Commit 9b5f6c9b authored by Harshad Shirwadkar's avatar Harshad Shirwadkar Committed by Theodore Ts'o
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ext4: make s_mount_flags modifications atomic 



Fast commit file system states are recorded in
sbi->s_mount_flags. Fast commit expects these bit manipulations to be
atomic. This patch adds helpers to make those modifications atomic.

Suggested-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarHarshad Shirwadkar <harshadshirwadkar@gmail.com>
Link: https://lore.kernel.org/r/20201106035911.1942128-21-harshadshirwadkar@gmail.com


Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent da0c5d26

fs/ext4/ext4.h

+29 −11
Original line number Diff line number Diff line
@@ -1419,16 +1419,6 @@ struct ext4_super_block { 


#ifdef __KERNEL__



/*

 * run-time mount flags

 */

#define EXT4_MF_MNTDIR_SAMPLED		0x0001

#define EXT4_MF_FS_ABORTED		0x0002	/* Fatal error detected */

#define EXT4_MF_FC_INELIGIBLE		0x0004	/* Fast commit ineligible */

#define EXT4_MF_FC_COMMITTING		0x0008	/* File system underoing a fast

						 * commit.

						 */



#ifdef CONFIG_FS_ENCRYPTION

#define DUMMY_ENCRYPTION_ENABLED(sbi) ((sbi)->s_dummy_enc_policy.policy != NULL)

#else
@@ -1463,7 +1453,7 @@ struct ext4_sb_info { 
	struct buffer_head * __rcu *s_group_desc;

	unsigned int s_mount_opt;

	unsigned int s_mount_opt2;

	unsigned int s_mount_flags;

	unsigned long s_mount_flags;

	unsigned int s_def_mount_opt;

	ext4_fsblk_t s_sb_block;

	atomic64_t s_resv_clusters;
@@ -1691,6 +1681,34 @@ static inline int ext4_valid_inum(struct super_block *sb, unsigned long ino) 
	_v;								   \

})



/*

 * run-time mount flags

 */

enum {

	EXT4_MF_MNTDIR_SAMPLED,

	EXT4_MF_FS_ABORTED,	/* Fatal error detected */

	EXT4_MF_FC_INELIGIBLE,	/* Fast commit ineligible */

	EXT4_MF_FC_COMMITTING	/* File system underoing a fast

				 * commit.

				 */

};



static inline void ext4_set_mount_flag(struct super_block *sb, int bit)

{

	set_bit(bit, &EXT4_SB(sb)->s_mount_flags);

}



static inline void ext4_clear_mount_flag(struct super_block *sb, int bit)

{

	clear_bit(bit, &EXT4_SB(sb)->s_mount_flags);

}



static inline int ext4_test_mount_flag(struct super_block *sb, int bit)

{

	return test_bit(bit, &EXT4_SB(sb)->s_mount_flags);

}





/*

 * Simulate_fail codes

 */

fs/ext4/fast_commit.c

+9 −9
Original line number Diff line number Diff line
@@ -261,7 +261,7 @@ void ext4_fc_mark_ineligible(struct super_block *sb, int reason) 
	    (EXT4_SB(sb)->s_mount_state & EXT4_FC_REPLAY))

		return;



	sbi->s_mount_flags |= EXT4_MF_FC_INELIGIBLE;

	ext4_set_mount_flag(sb, EXT4_MF_FC_INELIGIBLE);

	WARN_ON(reason >= EXT4_FC_REASON_MAX);

	sbi->s_fc_stats.fc_ineligible_reason_count[reason]++;

}
@@ -294,14 +294,14 @@ void ext4_fc_stop_ineligible(struct super_block *sb) 
	    (EXT4_SB(sb)->s_mount_state & EXT4_FC_REPLAY))

		return;



	EXT4_SB(sb)->s_mount_flags |= EXT4_MF_FC_INELIGIBLE;

	ext4_set_mount_flag(sb, EXT4_MF_FC_INELIGIBLE);

	atomic_dec(&EXT4_SB(sb)->s_fc_ineligible_updates);

}



static inline int ext4_fc_is_ineligible(struct super_block *sb)

{

	return (EXT4_SB(sb)->s_mount_flags & EXT4_MF_FC_INELIGIBLE) ||

		atomic_read(&EXT4_SB(sb)->s_fc_ineligible_updates);

	return (ext4_test_mount_flag(sb, EXT4_MF_FC_INELIGIBLE) ||

		atomic_read(&EXT4_SB(sb)->s_fc_ineligible_updates));

}



/*
@@ -349,7 +349,7 @@ static int ext4_fc_track_template( 
	spin_lock(&sbi->s_fc_lock);

	if (list_empty(&EXT4_I(inode)->i_fc_list))

		list_add_tail(&EXT4_I(inode)->i_fc_list,

				(sbi->s_mount_flags & EXT4_MF_FC_COMMITTING) ?

				(ext4_test_mount_flag(inode->i_sb, EXT4_MF_FC_COMMITTING)) ?

				&sbi->s_fc_q[FC_Q_STAGING] :

				&sbi->s_fc_q[FC_Q_MAIN]);

	spin_unlock(&sbi->s_fc_lock);
@@ -402,7 +402,7 @@ static int __track_dentry_update(struct inode *inode, void *arg, bool update) 
	node->fcd_name.len = dentry->d_name.len;



	spin_lock(&sbi->s_fc_lock);

	if (sbi->s_mount_flags & EXT4_MF_FC_COMMITTING)

	if (ext4_test_mount_flag(inode->i_sb, EXT4_MF_FC_COMMITTING))

		list_add_tail(&node->fcd_list,

				&sbi->s_fc_dentry_q[FC_Q_STAGING]);

	else
@@ -857,7 +857,7 @@ static int ext4_fc_submit_inode_data_all(journal_t *journal) 
	int ret = 0;



	spin_lock(&sbi->s_fc_lock);

	sbi->s_mount_flags |= EXT4_MF_FC_COMMITTING;

	ext4_set_mount_flag(sb, EXT4_MF_FC_COMMITTING);

	list_for_each(pos, &sbi->s_fc_q[FC_Q_MAIN]) {

		ei = list_entry(pos, struct ext4_inode_info, i_fc_list);

		ext4_set_inode_state(&ei->vfs_inode, EXT4_STATE_FC_COMMITTING);
@@ -1206,8 +1206,8 @@ static void ext4_fc_cleanup(journal_t *journal, int full) 
	list_splice_init(&sbi->s_fc_q[FC_Q_STAGING],

				&sbi->s_fc_q[FC_Q_STAGING]);



	sbi->s_mount_flags &= ~EXT4_MF_FC_COMMITTING;

	sbi->s_mount_flags &= ~EXT4_MF_FC_INELIGIBLE;

	ext4_clear_mount_flag(sb, EXT4_MF_FC_COMMITTING);

	ext4_clear_mount_flag(sb, EXT4_MF_FC_INELIGIBLE);



	if (full)

		sbi->s_fc_bytes = 0;

fs/ext4/file.c

+2 −2
Original line number Diff line number Diff line
@@ -780,13 +780,13 @@ static int ext4_sample_last_mounted(struct super_block *sb, 
	handle_t *handle;

	int err;



	if (likely(sbi->s_mount_flags & EXT4_MF_MNTDIR_SAMPLED))

	if (likely(ext4_test_mount_flag(sb, EXT4_MF_MNTDIR_SAMPLED)))

		return 0;



	if (sb_rdonly(sb) || !sb_start_intwrite_trylock(sb))

		return 0;



	sbi->s_mount_flags |= EXT4_MF_MNTDIR_SAMPLED;

	ext4_set_mount_flag(sb, EXT4_MF_MNTDIR_SAMPLED);

	/*

	 * Sample where the filesystem has been mounted and

	 * store it in the superblock for sysadmin convenience

fs/ext4/fsync.c

+1 −1
Original line number Diff line number Diff line
@@ -143,7 +143,7 @@ int ext4_sync_file(struct file *file, loff_t start, loff_t end, int datasync) 
	if (sb_rdonly(inode->i_sb)) {

		/* Make sure that we read updated s_mount_flags value */

		smp_rmb();

		if (sbi->s_mount_flags & EXT4_MF_FS_ABORTED)

		if (ext4_test_mount_flag(inode->i_sb, EXT4_MF_FS_ABORTED))

			ret = -EROFS;

		goto out;

	}

fs/ext4/inode.c

+2 −2
Original line number Diff line number Diff line
@@ -2442,7 +2442,7 @@ static int mpage_map_and_submit_extent(handle_t *handle, 
			struct super_block *sb = inode->i_sb;



			if (ext4_forced_shutdown(EXT4_SB(sb)) ||

			    EXT4_SB(sb)->s_mount_flags & EXT4_MF_FS_ABORTED)

			    ext4_test_mount_flag(sb, EXT4_MF_FS_ABORTED))

				goto invalidate_dirty_pages;

			/*

			 * Let the uper layers retry transient errors.
@@ -2676,7 +2676,7 @@ static int ext4_writepages(struct address_space *mapping, 
	 * the stack trace.

	 */

	if (unlikely(ext4_forced_shutdown(EXT4_SB(mapping->host->i_sb)) ||

		     sbi->s_mount_flags & EXT4_MF_FS_ABORTED)) {

		     ext4_test_mount_flag(inode->i_sb, EXT4_MF_FS_ABORTED))) {

		ret = -EROFS;

		goto out_writepages;

	}