From: Valerie Aurora <val@xxxxxxxxxxxxxxxxx> BugLink: https://bugs.launchpad.net/bugs/897421 Signed-off-by: Valerie Aurora <val@xxxxxxxxxxxxxxxxx> Cc: Kamal Mostafa <kamal@xxxxxxxxxxxxx> Tested-by: Peter M. Petrakis <peter.petrakis@xxxxxxxxxxxxx> [kamal@xxxxxxxxxxxxx: patch restructure] Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx> --- fs/super.c | 18 ++++++++++++++++++ 1 files changed, 18 insertions(+), 0 deletions(-) diff --git a/fs/super.c b/fs/super.c index 5629d06..a56696b 100644 --- a/fs/super.c +++ b/fs/super.c @@ -1140,6 +1140,24 @@ out: * Syncs the super to make sure the filesystem is consistent and calls the fs's * freeze_fs. Subsequent calls to this without first thawing the fs will return * -EBUSY. + * + * During this function, sb->s_frozen goes through these values: + * + * SB_UNFROZEN: File system is normal, all writes progress as usual. + * + * SB_FREEZE_WRITE: The file system is in the process of being frozen + * and any remaining out-standing writes are being synced. Writes + * that complete in-process writes should be permitted but new ones + * should be blocked. + * + * SB_FREEZE_TRANS: The file system is frozen. The ->freeze_fs and + * ->unfreeze_fs ops are the only operations permitted to write to the + * file system in this state. + * + * sb->s_frozen is protected by sb->s_umount. Additionally, + * SB_FREEZE_WRITE is only temporarily set during freeze/thaw while + * holding sb->s_umount for writing, so any other callers holding + * sb->s_umount will never see this state. */ int freeze_super(struct super_block *sb) { -- 1.7.5.4 -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
