ext4: notify sysfs on errors_count value change

After s_error_count is incremented, signal the change in the
corresponding sysfs attribute via sysfs_notify. This allows userspace to
poll() on changes to /sys/fs/ext4/*/errors_count.

[ Moved call of ext4_notify_error_sysfs() to flush_stashed_error_work()
  to avoid BUG's caused by calling sysfs_notify trying to sleep after
  being called from an invalid context. -- TYT ]

Signed-off-by: Jonathan Davies <jonathan.davies@nutanix.com>
Link: https://lore.kernel.org/r/20210611140209.28903-1-jonathan.davies@nutanix.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 8ff4ae3..3c51e24 100644 (file)
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -3624,6 +3624,7 @@ extern const struct inode_operations ext4_symlink_inode_operations;
 extern const struct inode_operations ext4_fast_symlink_inode_operations;
 
 /* sysfs.c */
+extern void ext4_notify_error_sysfs(struct ext4_sb_info *sbi);
 extern int ext4_register_sysfs(struct super_block *sb);
 extern void ext4_unregister_sysfs(struct super_block *sb);
 extern int __init ext4_init_sysfs(void);

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 9e0fb79..2034463 100644 (file)
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -718,6 +718,7 @@ static void flush_stashed_error_work(struct work_struct *work)
                        goto write_directly;
                }
                jbd2_journal_stop(handle);
+               ext4_notify_error_sysfs(sbi);
                return;
        }
 write_directly:
@@ -726,6 +727,7 @@ write_directly:
         * out and hope for the best.
         */
        ext4_commit_super(sbi->s_sb);
+       ext4_notify_error_sysfs(sbi);
 }
 
 #define ext4_error_ratelimit(sb)                                       \

diff --git a/fs/ext4/sysfs.c b/fs/ext4/sysfs.c
index 55fcab6..2314f74 100644 (file)
--- a/fs/ext4/sysfs.c
+++ b/fs/ext4/sysfs.c
@@ -506,6 +506,11 @@ static struct kobj_type ext4_feat_ktype = {
        .release        = (void (*)(struct kobject *))kfree,
 };
 
+void ext4_notify_error_sysfs(struct ext4_sb_info *sbi)
+{
+       sysfs_notify(&sbi->s_kobj, NULL, "errors_count");
+}
+
 static struct kobject *ext4_root;
 
 static struct kobject *ext4_feat;