Commit 4d326646 authored by Harshad Shirwadkar's avatar Harshad Shirwadkar Committed by Theodore Ts'o
Browse files

ext4: for committing inode, make ext4_fc_track_inode wait 



If the inode that's being requested to track using ext4_fc_track_inode
is being committed, then wait until the inode finishes the
commit. Also, add calls to ext4_fc_track_inode at the right places.
With this patch, now calling ext4_reserve_inode_write() results in
inode being tracked for next fast commit. This ensures that by the
time ext4_reserve_inode_write() returns, it is ready to be modified
and won't be committed until the corresponding handle is open.

A subtle lock ordering requirement with i_data_sem (which is
documented in the code) requires that ext4_fc_track_inode() be called
before grabbing i_data_sem. So, this patch also adds explicit
ext4_fc_track_inode() calls in places where i_data_sem grabbed.

Signed-off-by: default avatarHarshad Shirwadkar <harshadshirwadkar@gmail.com>
Link: https://patch.msgid.link/20250508175908.1004880-3-harshadshirwadkar@gmail.com


Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent 834224e8

fs/ext4/fast_commit.c

+35 −0
Original line number Diff line number Diff line
@@ -12,6 +12,7 @@ 
#include "ext4_extents.h"

#include "mballoc.h"



#include <linux/lockdep.h>

/*

 * Ext4 Fast Commits

 * -----------------
@@ -570,6 +571,8 @@ static int __track_inode(handle_t *handle, struct inode *inode, void *arg, 


void ext4_fc_track_inode(handle_t *handle, struct inode *inode)

{

	struct ext4_inode_info *ei = EXT4_I(inode);

	wait_queue_head_t *wq;

	int ret;



	if (S_ISDIR(inode->i_mode))
@@ -587,6 +590,38 @@ void ext4_fc_track_inode(handle_t *handle, struct inode *inode) 
	if (ext4_test_mount_flag(inode->i_sb, EXT4_MF_FC_INELIGIBLE))

		return;



	if (!list_empty(&ei->i_fc_list))

		return;



	/*

	 * If we come here, we may sleep while waiting for the inode to

	 * commit. We shouldn't be holding i_data_sem when we go to sleep since

	 * the commit path needs to grab the lock while committing the inode.

	 */

	lockdep_assert_not_held(&ei->i_data_sem);



	while (ext4_test_inode_state(inode, EXT4_STATE_FC_COMMITTING)) {

#if (BITS_PER_LONG < 64)

		DEFINE_WAIT_BIT(wait, &ei->i_state_flags,

				EXT4_STATE_FC_COMMITTING);

		wq = bit_waitqueue(&ei->i_state_flags,

				   EXT4_STATE_FC_COMMITTING);

#else

		DEFINE_WAIT_BIT(wait, &ei->i_flags,

				EXT4_STATE_FC_COMMITTING);

		wq = bit_waitqueue(&ei->i_flags,

				   EXT4_STATE_FC_COMMITTING);

#endif

		prepare_to_wait(wq, &wait.wq_entry, TASK_UNINTERRUPTIBLE);

		if (ext4_test_inode_state(inode, EXT4_STATE_FC_COMMITTING))

			schedule();

		finish_wait(wq, &wait.wq_entry);

	}



	/*

	 * From this point on, this inode will not be committed either

	 * by fast or full commit as long as the handle is open.

	 */

	ret = ext4_fc_track_template(handle, inode, __track_inode, NULL, 1);

	trace_ext4_fc_track_inode(handle, inode, ret);

}

fs/ext4/inline.c

+1 −0
Original line number Diff line number Diff line
@@ -601,6 +601,7 @@ static int ext4_convert_inline_data_to_extent(struct address_space *mapping, 
			goto out;

	}



	ext4_fc_track_inode(handle, inode);

	ret = ext4_destroy_inline_data_nolock(handle, inode);

	if (ret)

		goto out;

fs/ext4/inode.c

+5 −0
Original line number Diff line number Diff line
@@ -696,6 +696,8 @@ int ext4_map_blocks(handle_t *handle, struct inode *inode, 
		if (!(flags & EXT4_GET_BLOCKS_CONVERT_UNWRITTEN))

			return retval;





	ext4_fc_track_inode(handle, inode);

	/*

	 * New blocks allocate and/or writing to unwritten extent

	 * will possibly result in updating i_data, so we take
@@ -4072,6 +4074,7 @@ int ext4_punch_hole(struct file *file, loff_t offset, loff_t length) 
	if (end_lblk > start_lblk) {

		ext4_lblk_t hole_len = end_lblk - start_lblk;



		ext4_fc_track_inode(handle, inode);

		down_write(&EXT4_I(inode)->i_data_sem);

		ext4_discard_preallocations(inode);
@@ -4224,6 +4227,7 @@ int ext4_truncate(struct inode *inode) 
	if (err)

		goto out_stop;



	ext4_fc_track_inode(handle, inode);

	down_write(&EXT4_I(inode)->i_data_sem);



	ext4_discard_preallocations(inode);
@@ -5895,6 +5899,7 @@ ext4_reserve_inode_write(handle_t *handle, struct inode *inode, 
			brelse(iloc->bh);

			iloc->bh = NULL;

		}

		ext4_fc_track_inode(handle, inode);

	}

	ext4_std_error(inode->i_sb, err);

	return err;