[PATCH 10/19] ext4: Convert to new freezing mechanism
From: Jan Kara <jack@suse.cz>
Date: 2012-03-05 16:01:08
Also in:
linux-fsdevel, lkml
Subsystem:
ext4 file system, filesystems (vfs and infrastructure), the rest · Maintainers:
"Theodore Ts'o", Alexander Viro, Christian Brauner, Linus Torvalds
We remove most of frozen checks since upper layer takes care of blocking all writes. We only have to handle protection in ext4_page_mkwrite() in a special way because we cannot use generic block_page_mkwrite(). CC: linux-ext4@vger.kernel.org CC: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by: Jan Kara <jack@suse.cz> --- fs/ext4/inode.c | 7 ++----- fs/ext4/super.c | 29 +++++------------------------ 2 files changed, 7 insertions(+), 29 deletions(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index feaa82f..c65baf9 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c@@ -4593,11 +4593,7 @@ int ext4_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf) get_block_t *get_block; int retries = 0; - /* - * This check is racy but catches the common case. We rely on - * __block_page_mkwrite() to do a reliable check. - */ - vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE); + sb_start_pagefault(inode->i_sb); /* Delalloc case is easy... */ if (test_opt(inode->i_sb, DELALLOC) && !ext4_should_journal_data(inode) &&
@@ -4665,5 +4661,6 @@ retry_alloc: out_ret: ret = block_page_mkwrite_return(ret); out: + sb_end_pagefault(inode->i_sb); return ret; }
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 502c61f..0f1024a 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c@@ -289,33 +289,17 @@ static void ext4_put_nojournal(handle_t *handle) * journal_end calls result in the superblock being marked dirty, so * that sync() will call the filesystem's write_super callback if * appropriate. - * - * To avoid j_barrier hold in userspace when a user calls freeze(), - * ext4 prevents a new handle from being started by s_frozen, which - * is in an upper layer. */ handle_t *ext4_journal_start_sb(struct super_block *sb, int nblocks) { journal_t *journal; - handle_t *handle; trace_ext4_journal_start(sb, nblocks, _RET_IP_); if (sb->s_flags & MS_RDONLY) return ERR_PTR(-EROFS); + WARN_ON(sb->s_writers.frozen == SB_FREEZE_COMPLETE); journal = EXT4_SB(sb)->s_journal; - handle = ext4_journal_current_handle(); - - /* - * If a handle has been started, it should be allowed to - * finish, otherwise deadlock could happen between freeze - * and others(e.g. truncate) due to the restart of the - * journal handle if the filesystem is forzen and active - * handles are not stopped. - */ - if (!handle) - vfs_check_frozen(sb, SB_FREEZE_TRANS); - if (!journal) return ext4_get_nojournal(); /*
@@ -4280,10 +4264,8 @@ int ext4_force_commit(struct super_block *sb) return 0; journal = EXT4_SB(sb)->s_journal; - if (journal) { - vfs_check_frozen(sb, SB_FREEZE_TRANS); + if (journal) ret = ext4_journal_force_commit(journal); - } return ret; }
@@ -4315,9 +4297,8 @@ static int ext4_sync_fs(struct super_block *sb, int wait) * gives us a chance to flush the journal completely and mark the fs clean. * * Note that only this function cannot bring a filesystem to be in a clean - * state independently, because ext4 prevents a new handle from being started - * by @sb->s_frozen, which stays in an upper layer. It thus needs help from - * the upper layer. + * state independently. It relies on upper layer to stop all data & metadata + * modifications. */ static int ext4_freeze(struct super_block *sb) {
@@ -4344,7 +4325,7 @@ static int ext4_freeze(struct super_block *sb) EXT4_CLEAR_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_RECOVER); error = ext4_commit_super(sb, 1); out: - /* we rely on s_frozen to stop further updates */ + /* we rely on upper layer to stop further updates */ jbd2_journal_unlock_updates(EXT4_SB(sb)->s_journal); return error; }
--
1.7.1