[RHEL7,COMMIT] ms/jbd2: introduce jbd2_inode dirty range scoping

Submitted by Konstantin Khorenko on Oct. 25, 2019, 10:03 p.m.

Details

Message ID 201910252203.x9PM3KZs007032@finist-ce7.sw.ru
State New
Series "ms/jbd2: introduce jbd2_inode dirty range scoping"
Headers show

Commit Message

Konstantin Khorenko Oct. 25, 2019, 10:03 p.m.
The commit is pushed to "branch-rh7-3.10.0-1062.1.2.vz7.114.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-1062.1.2.vz7.114.10
------>
commit 69e7012e8e2031ec96fd80cce6f7013ee0c8db54
Author: Ross Zwisler <zwisler@chromium.org>
Date:   Sat Oct 26 01:03:19 2019 +0300

    ms/jbd2: introduce jbd2_inode dirty range scoping
    
    Currently both journal_submit_inode_data_buffers() and
    journal_finish_inode_data_buffers() operate on the entire address space
    of each of the inodes associated with a given journal entry.  The
    consequence of this is that if we have an inode where we are constantly
    appending dirty pages we can end up waiting for an indefinite amount of
    time in journal_finish_inode_data_buffers() while we wait for all the
    pages under writeback to be written out.
    
    The easiest way to cause this type of workload is do just dd from
    /dev/zero to a file until it fills the entire filesystem.  This can
    cause journal_finish_inode_data_buffers() to wait for the duration of
    the entire dd operation.
    
    We can improve this situation by scoping each of the inode dirty ranges
    associated with a given transaction.  We do this via the jbd2_inode
    structure so that the scoping is contained within jbd2 and so that it
    follows the lifetime and locking rules for that structure.
    
    This allows us to limit the writeback & wait in
    journal_submit_inode_data_buffers() and
    journal_finish_inode_data_buffers() respectively to the dirty range for
    a given struct jdb2_inode, keeping us from waiting forever if the inode
    in question is still being appended to.
    
    Signed-off-by: Ross Zwisler <zwisler@google.com>
    Signed-off-by: Theodore Ts'o <tytso@mit.edu>
    Reviewed-by: Jan Kara <jack@suse.cz>
    Cc: stable@vger.kernel.org
    
    (cherry picked from commit 6ba0e7dc64a5adcda2fbe65adc466891795d639e)
    Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
---
 fs/jbd2/commit.c      | 23 +++++++++++++++++------
 fs/jbd2/journal.c     |  4 ++++
 fs/jbd2/transaction.c | 49 ++++++++++++++++++++++++++++---------------------
 include/linux/jbd2.h  | 22 ++++++++++++++++++++++
 4 files changed, 71 insertions(+), 27 deletions(-)

Patch hide | download patch | download mbox

diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
index 06f1c8697f27..63a5f81a27f6 100644
--- a/fs/jbd2/commit.c
+++ b/fs/jbd2/commit.c
@@ -192,14 +192,15 @@  static int journal_wait_on_commit_record(journal_t *journal,
  * use writepages() because with dealyed allocation we may be doing
  * block allocation in writepages().
  */
-static int journal_submit_inode_data_buffers(struct address_space *mapping)
+static int journal_submit_inode_data_buffers(struct address_space *mapping,
+		loff_t dirty_start, loff_t dirty_end)
 {
 	int ret;
 	struct writeback_control wbc = {
 		.sync_mode =  WB_SYNC_ALL,
 		.nr_to_write = mapping->nrpages * 2,
-		.range_start = 0,
-		.range_end = i_size_read(mapping->host),
+		.range_start = dirty_start,
+		.range_end = dirty_end,
 	};
 
 	ret = generic_writepages(mapping, &wbc);
@@ -223,6 +224,9 @@  static int journal_submit_data_buffers(journal_t *journal,
 
 	spin_lock(&journal->j_list_lock);
 	list_for_each_entry(jinode, &commit_transaction->t_inode_list, i_list) {
+		loff_t dirty_start = jinode->i_dirty_start;
+		loff_t dirty_end = jinode->i_dirty_end;
+
 		if (!(jinode->i_flags & JI_WRITE_DATA))
 			continue;
 		mapping = jinode->i_vfs_inode->i_mapping;
@@ -235,7 +239,8 @@  static int journal_submit_data_buffers(journal_t *journal,
 		 * only allocated blocks here.
 		 */
 		trace_jbd2_submit_inode_data(jinode->i_vfs_inode);
-		err = journal_submit_inode_data_buffers(mapping);
+		err = journal_submit_inode_data_buffers(mapping, dirty_start,
+				dirty_end);
 		if (!ret)
 			ret = err;
 		spin_lock(&journal->j_list_lock);
@@ -262,12 +267,16 @@  static int journal_finish_inode_data_buffers(journal_t *journal,
 	/* For locking, see the comment in journal_submit_data_buffers() */
 	spin_lock(&journal->j_list_lock);
 	list_for_each_entry(jinode, &commit_transaction->t_inode_list, i_list) {
+		loff_t dirty_start = jinode->i_dirty_start;
+		loff_t dirty_end = jinode->i_dirty_end;
+
 		if (!(jinode->i_flags & JI_WAIT_DATA))
 			continue;
 		set_bit(__JI_COMMIT_RUNNING, &jinode->i_flags);
 		spin_unlock(&journal->j_list_lock);
-		err = filemap_fdatawait_keep_errors(
-				jinode->i_vfs_inode->i_mapping);
+		err = filemap_fdatawait_range_keep_errors(
+				jinode->i_vfs_inode->i_mapping, dirty_start,
+				dirty_end);
 		if (!ret)
 			ret = err;
 		spin_lock(&journal->j_list_lock);
@@ -287,6 +296,8 @@  static int journal_finish_inode_data_buffers(journal_t *journal,
 				&jinode->i_transaction->t_inode_list);
 		} else {
 			jinode->i_transaction = NULL;
+			jinode->i_dirty_start = 0;
+			jinode->i_dirty_end = 0;
 		}
 	}
 	spin_unlock(&journal->j_list_lock);
diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 977e8a4b5088..322cbc6cd71a 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -96,6 +96,8 @@  EXPORT_SYMBOL(jbd2_journal_try_to_free_buffers);
 EXPORT_SYMBOL(jbd2_journal_force_commit);
 EXPORT_SYMBOL(jbd2_journal_inode_add_write);
 EXPORT_SYMBOL(jbd2_journal_inode_add_wait);
+EXPORT_SYMBOL(jbd2_journal_inode_ranged_write);
+EXPORT_SYMBOL(jbd2_journal_inode_ranged_wait);
 EXPORT_SYMBOL(jbd2_journal_init_jbd_inode);
 EXPORT_SYMBOL(jbd2_journal_release_jbd_inode);
 EXPORT_SYMBOL(jbd2_journal_begin_ordered_truncate);
@@ -2592,6 +2594,8 @@  void jbd2_journal_init_jbd_inode(struct jbd2_inode *jinode, struct inode *inode)
 	jinode->i_next_transaction = NULL;
 	jinode->i_vfs_inode = inode;
 	jinode->i_flags = 0;
+	jinode->i_dirty_start = 0;
+	jinode->i_dirty_end = 0;
 	INIT_LIST_HEAD(&jinode->i_list);
 }
 
diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
index 55003633997c..279d72abdea5 100644
--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -2445,7 +2445,7 @@  void jbd2_journal_refile_buffer(journal_t *journal, struct journal_head *jh)
  * File inode in the inode list of the handle's transaction
  */
 static int jbd2_journal_file_inode(handle_t *handle, struct jbd2_inode *jinode,
-				   unsigned long flags)
+		unsigned long flags, loff_t start_byte, loff_t end_byte)
 {
 	transaction_t *transaction = handle->h_transaction;
 	journal_t *journal;
@@ -2457,26 +2457,17 @@  static int jbd2_journal_file_inode(handle_t *handle, struct jbd2_inode *jinode,
 	jbd_debug(4, "Adding inode %lu, tid:%d\n", jinode->i_vfs_inode->i_ino,
 			transaction->t_tid);
 
-	/*
-	 * First check whether inode isn't already on the transaction's
-	 * lists without taking the lock. Note that this check is safe
-	 * without the lock as we cannot race with somebody removing inode
-	 * from the transaction. The reason is that we remove inode from the
-	 * transaction only in journal_release_jbd_inode() and when we commit
-	 * the transaction. We are guarded from the first case by holding
-	 * a reference to the inode. We are safe against the second case
-	 * because if jinode->i_transaction == transaction, commit code
-	 * cannot touch the transaction because we hold reference to it,
-	 * and if jinode->i_next_transaction == transaction, commit code
-	 * will only file the inode where we want it.
-	 */
-	if ((jinode->i_transaction == transaction ||
-	    jinode->i_next_transaction == transaction) &&
-	    (jinode->i_flags & flags) == flags)
-		return 0;
-
 	spin_lock(&journal->j_list_lock);
 	jinode->i_flags |= flags;
+
+	if (jinode->i_dirty_end) {
+		jinode->i_dirty_start = min(jinode->i_dirty_start, start_byte);
+		jinode->i_dirty_end = max(jinode->i_dirty_end, end_byte);
+	} else {
+		jinode->i_dirty_start = start_byte;
+		jinode->i_dirty_end = end_byte;
+	}
+
 	/* Is inode already attached where we need it? */
 	if (jinode->i_transaction == transaction ||
 	    jinode->i_next_transaction == transaction)
@@ -2511,12 +2502,28 @@  static int jbd2_journal_file_inode(handle_t *handle, struct jbd2_inode *jinode,
 int jbd2_journal_inode_add_write(handle_t *handle, struct jbd2_inode *jinode)
 {
 	return jbd2_journal_file_inode(handle, jinode,
-				       JI_WRITE_DATA | JI_WAIT_DATA);
+			JI_WRITE_DATA | JI_WAIT_DATA, 0, LLONG_MAX);
 }
 
 int jbd2_journal_inode_add_wait(handle_t *handle, struct jbd2_inode *jinode)
 {
-	return jbd2_journal_file_inode(handle, jinode, JI_WAIT_DATA);
+	return jbd2_journal_file_inode(handle, jinode, JI_WAIT_DATA, 0,
+			LLONG_MAX);
+}
+
+int jbd2_journal_inode_ranged_write(handle_t *handle,
+		struct jbd2_inode *jinode, loff_t start_byte, loff_t length)
+{
+	return jbd2_journal_file_inode(handle, jinode,
+			JI_WRITE_DATA | JI_WAIT_DATA, start_byte,
+			start_byte + length - 1);
+}
+
+int jbd2_journal_inode_ranged_wait(handle_t *handle, struct jbd2_inode *jinode,
+		loff_t start_byte, loff_t length)
+{
+	return jbd2_journal_file_inode(handle, jinode, JI_WAIT_DATA,
+			start_byte, start_byte + length - 1);
 }
 
 /*
diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
index 06d7a6febe5b..3658fc0dfa64 100644
--- a/include/linux/jbd2.h
+++ b/include/linux/jbd2.h
@@ -403,6 +403,22 @@  struct jbd2_inode {
 
 	/* Flags of inode [j_list_lock] */
 	unsigned long i_flags;
+
+	/**
+	 * @i_dirty_start:
+	 *
+	 * Offset in bytes where the dirty range for this inode starts.
+	 * [j_list_lock]
+	 */
+	loff_t i_dirty_start;
+
+	/**
+	 * @i_dirty_end:
+	 *
+	 * Inclusive offset in bytes where the dirty range for this inode
+	 * ends. [j_list_lock]
+	 */
+	loff_t i_dirty_end;
 };
 
 struct jbd2_revoke_table_s;
@@ -1180,6 +1196,12 @@  extern int	   jbd2_journal_force_commit(journal_t *);
 extern int	   jbd2_journal_force_commit_nested(journal_t *);
 extern int	   jbd2_journal_inode_add_write(handle_t *handle, struct jbd2_inode *inode);
 extern int	   jbd2_journal_inode_add_wait(handle_t *handle, struct jbd2_inode *inode);
+extern int	   jbd2_journal_inode_ranged_write(handle_t *handle,
+			struct jbd2_inode *inode, loff_t start_byte,
+			loff_t length);
+extern int	   jbd2_journal_inode_ranged_wait(handle_t *handle,
+			struct jbd2_inode *inode, loff_t start_byte,
+			loff_t length);
 extern int	   jbd2_journal_begin_ordered_truncate(journal_t *journal,
 				struct jbd2_inode *inode, loff_t new_size);
 extern void	   jbd2_journal_init_jbd_inode(struct jbd2_inode *jinode, struct inode *inode);