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Message-ID: <20241213151029.qeuctijrbibqoqp5@quack3> Date: Fri, 13 Dec 2024 16:10:29 +0100 From: Jan Kara <jack@...e.cz> To: Harshad Shirwadkar <harshadshirwadkar@...il.com> Cc: linux-ext4@...r.kernel.org, tytso@....edu, jack@...e.cz, harshads@...gle.com Subject: Re: [PATCH v7 2/9] ext4: for committing inode, make ext4_fc_track_inode wait On Thu 12-12-24 23:00:43, Jan Kara wrote: > On Sun 18-08-24 04:03:49, Harshad Shirwadkar wrote: > > + > > + 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); > > + } > > But what protects us from fastcommit setting EXT4_STATE_FC_COMMITTING at > this moment before we call ext4_fc_track_template(). Don't you need > to grab sbi->s_fc_lock and hold it until the inode is attached to the > fastcommit? > > I might be missing something so some documentation (like a comment here) > would be nice to explain what are you actually trying to achieve with the > waiting... Ah, I see now. In patch 4 you make setting of EXT4_STATE_FC_COMMITTING protected by journal locking so holding a handle open protects us. Good. But please comment about it in the changelog. Honza -- Jan Kara <jack@...e.com> SUSE Labs, CR
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