From 994f567b2e99c82913a279ff438269c771b68a4b Mon Sep 17 00:00:00 2001 From: Dmitry Monakhov Date: Sat, 29 Sep 2012 00:41:21 -0400 Subject: [PATCH 05/13] ext4: serialize dio nonlocked reads with defrag workers Inode's block defrag and ext4_change_inode_journal_flag() may affect nonlocked DIO reads result, so proper synchronization required. - Add missed inode_dio_wait() calls where appropriate - Check inode state under extra i_dio_count reference. Reviewed-by: Jan Kara Signed-off-by: Dmitry Monakhov Signed-off-by: "Theodore Ts'o" (cherry picked from commit 17335dcc471199717839b2fa3492ca36f70f1168) Conflicts: fs/ext4/move_extent.c --- fs/ext4/ext4.h | 17 +++++++++++++++++ fs/ext4/indirect.c | 14 ++++++++++++++ fs/ext4/inode.c | 5 +++++ fs/ext4/move_extent.c | 8 ++++++++ 4 files changed, 44 insertions(+) diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 7687d15..3e740e9 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -1352,6 +1352,8 @@ enum { EXT4_STATE_DIO_UNWRITTEN, /* need convert on dio done*/ EXT4_STATE_NEWENTRY, /* File just added to dir */ EXT4_STATE_DELALLOC_RESERVED, /* blks already reserved for delalloc */ + EXT4_STATE_DIOREAD_LOCK, /* Disable support for dio read + nolocking */ }; #define EXT4_INODE_BIT_FNS(name, field, offset) \ @@ -2459,6 +2461,21 @@ static inline void set_bitmap_uptodate(struct buffer_head *bh) set_bit(BH_BITMAP_UPTODATE, &(bh)->b_state); } +/* + * Disable DIO read nolock optimization, so new dioreaders will be forced + * to grab i_mutex + */ +static inline void ext4_inode_block_unlocked_dio(struct inode *inode) +{ + ext4_set_inode_state(inode, EXT4_STATE_DIOREAD_LOCK); + smp_mb(); +} +static inline void ext4_inode_resume_unlocked_dio(struct inode *inode) +{ + smp_mb(); + ext4_clear_inode_state(inode, EXT4_STATE_DIOREAD_LOCK); +} + #define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1) /* For ioend & aio unwritten conversion wait queues */ diff --git a/fs/ext4/indirect.c b/fs/ext4/indirect.c index 61f13e5..8d849da 100644 --- a/fs/ext4/indirect.c +++ b/fs/ext4/indirect.c @@ -810,11 +810,25 @@ retry: if (unlikely(!list_empty(&ei->i_completed_io_list))) ext4_flush_completed_IO(inode); + /* + * Nolock dioread optimization may be dynamically disabled + * via ext4_inode_block_unlocked_dio(). Check inode's state + * while holding extra i_dio_count ref. + */ + atomic_inc(&inode->i_dio_count); + smp_mb(); + if (unlikely(ext4_test_inode_state(inode, + EXT4_STATE_DIOREAD_LOCK))) { + inode_dio_done(inode); + goto locked; + } ret = __blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov, offset, nr_segs, ext4_get_block, NULL, NULL, 0); + inode_dio_done(inode); } else { +locked: ret = blockdev_direct_IO(rw, iocb, inode, iov, offset, nr_segs, ext4_get_block); diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index dd3fd23..2bd7526 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -4706,6 +4706,10 @@ int ext4_change_inode_journal_flag(struct inode *inode, int val) return err; } + /* Wait for all existing dio workers */ + ext4_inode_block_unlocked_dio(inode); + inode_dio_wait(inode); + jbd2_journal_lock_updates(journal); /* @@ -4725,6 +4729,7 @@ int ext4_change_inode_journal_flag(struct inode *inode, int val) ext4_set_aops(inode); jbd2_journal_unlock_updates(journal); + ext4_inode_resume_unlocked_dio(inode); /* Finally we can mark the inode as dirty. */ diff --git a/fs/ext4/move_extent.c b/fs/ext4/move_extent.c index c5826c6..fd1e32e 100644 --- a/fs/ext4/move_extent.c +++ b/fs/ext4/move_extent.c @@ -1214,6 +1214,12 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp, /* Protect orig and donor inodes against a truncate */ mext_inode_double_lock(orig_inode, donor_inode); + /* Wait for all existing dio workers */ + ext4_inode_block_unlocked_dio(orig_inode); + ext4_inode_block_unlocked_dio(donor_inode); + inode_dio_wait(orig_inode); + inode_dio_wait(donor_inode); + /* Protect extent tree against block allocations via delalloc */ double_down_write_data_sem(orig_inode, donor_inode); /* Check the filesystem environment whether move_extent can be done */ @@ -1413,6 +1419,8 @@ out: kfree(holecheck_path); } double_up_write_data_sem(orig_inode, donor_inode); + ext4_inode_resume_unlocked_dio(orig_inode); + ext4_inode_resume_unlocked_dio(donor_inode); mext_inode_double_unlock(orig_inode, donor_inode); return ret; -- 1.7.12.rc0.22.gcdd159b