We remove most of frozen checks since upper layer takes care of blocking all writes. We have to handle protection in ext4_page_mkwrite() in a special way because we cannot use generic block_page_mkwrite(). Also we add a freeze protection to ext4_evict_inode() so that iput() of unlinked inode cannot modify a frozen filesystem (we cannot easily instrument ext4_journal_start() / ext4_journal_stop() with freeze protection because we are missing the superblock pointer in ext4_journal_stop() in nojournal mode). CC: linux-ext4@xxxxxxxxxxxxxxx CC: "Theodore Ts'o" <tytso@xxxxxxx> BugLink: https://bugs.launchpad.net/bugs/897421 Tested-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx> Tested-by: Peter M. Petrakis <peter.petrakis@xxxxxxxxxxxxx> Tested-by: Dann Frazier <dann.frazier@xxxxxxxxxxxxx> Tested-by: Massimo Morana <massimo.morana@xxxxxxxxxxxxx> Signed-off-by: Jan Kara <jack@xxxxxxx> --- fs/ext4/inode.c | 15 ++++++++++----- fs/ext4/mmp.c | 14 ++++++++++---- fs/ext4/super.c | 31 +++++++------------------------ 3 files changed, 27 insertions(+), 33 deletions(-) diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 07eaf56..4884127 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -166,6 +166,11 @@ void ext4_evict_inode(struct inode *inode) if (is_bad_inode(inode)) goto no_delete; + /* + * Protect us against freezing - iput() caller didn't have to have any + * protection against it + */ + sb_start_intwrite(inode->i_sb); handle = ext4_journal_start(inode, ext4_blocks_for_truncate(inode)+3); if (IS_ERR(handle)) { ext4_std_error(inode->i_sb, PTR_ERR(handle)); @@ -175,6 +180,7 @@ void ext4_evict_inode(struct inode *inode) * cleaned up. */ ext4_orphan_del(NULL, inode); + sb_end_intwrite(inode->i_sb); goto no_delete; } @@ -206,6 +212,7 @@ void ext4_evict_inode(struct inode *inode) stop_handle: ext4_journal_stop(handle); ext4_orphan_del(NULL, inode); + sb_end_intwrite(inode->i_sb); goto no_delete; } } @@ -234,6 +241,7 @@ void ext4_evict_inode(struct inode *inode) else ext4_free_inode(handle, inode); ext4_journal_stop(handle); + sb_end_intwrite(inode->i_sb); return; no_delete: ext4_clear_inode(inode); /* We must guarantee clearing of inode... */ @@ -4606,11 +4614,7 @@ 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) && @@ -4678,5 +4682,6 @@ retry_alloc: out_ret: ret = block_page_mkwrite_return(ret); out: + sb_end_pagefault(inode->i_sb); return ret; } diff --git a/fs/ext4/mmp.c b/fs/ext4/mmp.c index ed6548d..4f63f90 100644 --- a/fs/ext4/mmp.c +++ b/fs/ext4/mmp.c @@ -10,14 +10,20 @@ * Write the MMP block using WRITE_SYNC to try to get the block on-disk * faster. */ -static int write_mmp_block(struct buffer_head *bh) +static int write_mmp_block(struct super_block *sb, struct buffer_head *bh) { + /* + * We protect against freezing so that we don't create dirty buffers + * on frozen filesystem. + */ + sb_start_write(sb); mark_buffer_dirty(bh); lock_buffer(bh); bh->b_end_io = end_buffer_write_sync; get_bh(bh); submit_bh(WRITE_SYNC, bh); wait_on_buffer(bh); + sb_end_write(sb); if (unlikely(!buffer_uptodate(bh))) return 1; @@ -120,7 +126,7 @@ static int kmmpd(void *data) mmp->mmp_time = cpu_to_le64(get_seconds()); last_update_time = jiffies; - retval = write_mmp_block(bh); + retval = write_mmp_block(sb, bh); /* * Don't spew too many error messages. Print one every * (s_mmp_update_interval * 60) seconds. @@ -200,7 +206,7 @@ static int kmmpd(void *data) mmp->mmp_seq = cpu_to_le32(EXT4_MMP_SEQ_CLEAN); mmp->mmp_time = cpu_to_le64(get_seconds()); - retval = write_mmp_block(bh); + retval = write_mmp_block(sb, bh); failed: kfree(data); @@ -299,7 +305,7 @@ skip: seq = mmp_new_seq(); mmp->mmp_seq = cpu_to_le32(seq); - retval = write_mmp_block(bh); + retval = write_mmp_block(sb, bh); if (retval) goto failed; diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 35b5954..cd6a516 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -290,33 +290,17 @@ 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(); /* @@ -2633,6 +2617,7 @@ static int ext4_run_li_request(struct ext4_li_request *elr) sb = elr->lr_super; ngroups = EXT4_SB(sb)->s_groups_count; + sb_start_write(sb); for (group = elr->lr_next_group; group < ngroups; group++) { gdp = ext4_get_group_desc(sb, group, NULL); if (!gdp) { @@ -2659,6 +2644,7 @@ static int ext4_run_li_request(struct ext4_li_request *elr) elr->lr_next_sched = jiffies + elr->lr_timeout; elr->lr_next_group = group + 1; } + sb_end_write(sb); return ret; } @@ -4135,10 +4121,8 @@ 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; } @@ -4170,9 +4154,8 @@ 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) { @@ -4199,7 +4182,7 @@ 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 -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
