lwn.git/fs/jbd2/journal.c, branch docs-5.6

Merge branch 'jk/jbd2-revoke-overflow'

2019-11-05T21:02:20+00:00

jbd2: Reserve space for revoke descriptor blocks

2019-11-05T21:00:48+00:00

Extend functions for starting, extending, and restarting transaction handles to take number of revoke records handle must be able to accommodate. These functions then make sure transaction has enough credits to be able to store resulting revoke descriptor blocks. Also revoke code tracks number of revoke records created by a handle to catch situation where some place didn't reserve enough space for revoke records. Similarly to standard transaction credits, space for unused reserved revoke records is released when the handle is stopped. On the ext4 side we currently take a simplistic approach of reserving space for 1024 revoke records for any transaction. This grows amount of credits reserved for each handle only by a few and is enough for any normal workload so that we don't hit warnings in jbd2. We will refine the logic in following commits. Signed-off-by: Jan Kara Link: https://lore.kernel.org/r/20191105164437.32602-20-jack@suse.cz Signed-off-by: Theodore Ts'o

jbd2: Account descriptor blocks into t_outstanding_credits

2019-11-05T21:00:48+00:00

Currently, journal descriptor blocks were not accounted in transaction->t_outstanding_credits and we were just leaving some slack space in the journal for them (in jbd2_log_space_left() and jbd2_space_needed()). This is making proper accounting (and reservation we want to add) of descriptor blocks difficult so switch to accounting descriptor blocks in transaction->t_outstanding_credits and just reserve the same amount of credits in t_outstanding credits for journal descriptor blocks when creating transaction. Signed-off-by: Jan Kara Link: https://lore.kernel.org/r/20191105164437.32602-18-jack@suse.cz Signed-off-by: Theodore Ts'o

jbd2: Completely fill journal descriptor blocks

2019-11-05T17:13:25+00:00

With 32-bit block numbers, we don't allocate the array for journal buffer heads large enough for corresponding descriptor tags to fill the descriptor block. Thus we end up writing out half-full descriptor blocks to the journal unnecessarily growing the transaction. Fix the logic to allocate the array large enough. Signed-off-by: Jan Kara Link: https://lore.kernel.org/r/20191105164437.32602-3-jack@suse.cz Signed-off-by: Theodore Ts'o

jbd2: Free journal head outside of locked region

2019-10-21T13:16:46+00:00

On PREEMPT_RT bit-spinlocks have the same semantics as on PREEMPT_RT=n, i.e. they disable preemption. That means functions which are not safe to be called in preempt disabled context on RT trigger a might_sleep() assert. The journal head bit spinlock is mostly held for short code sequences with trivial RT safe functionality, except for one place: jbd2_journal_put_journal_head() invokes __journal_remove_journal_head() with the journal head bit spinlock held. __journal_remove_journal_head() invokes kmem_cache_free() which must not be called with preemption disabled on RT. Jan suggested to rework the removal function so the actual free happens outside the bit-spinlocked region. Split it into two parts: - Do the sanity checks and the buffer head detach under the lock - Do the actual free after dropping the lock There is error case handling in the free part which needs to dereference the b_size field of the now detached buffer head. Due to paranoia (caused by ignorance) the size is retrieved in the detach function and handed into the free function. Might be over-engineered, but better safe than sorry. This makes the journal head bit-spinlock usage RT compliant and also avoids nested locking which is not covered by lockdep. Suggested-by: Jan Kara Signed-off-by: Thomas Gleixner Cc: linux-ext4@vger.kernel.org Cc: "Theodore Ts'o" Cc: Jan Kara Signed-off-by: Jan Kara Link: https://lore.kernel.org/r/20190809124233.13277-8-jack@suse.cz Signed-off-by: Theodore Ts'o

jbd2: Make state lock a spinlock

2019-10-21T13:16:46+00:00

Bit-spinlocks are problematic on PREEMPT_RT if functions which might sleep on RT, e.g. spin_lock(), alloc/free(), are invoked inside the lock held region because bit spinlocks disable preemption even on RT. A first attempt was to replace state lock with a spinlock placed in struct buffer_head and make the locking conditional on PREEMPT_RT and DEBUG_BIT_SPINLOCKS. Jan pointed out that there is a 4 byte hole in struct journal_head where a regular spinlock fits in and he would not object to convert the state lock to a spinlock unconditionally. Aside of solving the RT problem, this also gains lockdep coverage for the journal head state lock (bit-spinlocks are not covered by lockdep as it's hard to fit a lockdep map into a single bit). The trivial change would have been to convert the jbd_*lock_bh_state() inlines, but that comes with the downside that these functions take a buffer head pointer which needs to be converted to a journal head pointer which adds another level of indirection. As almost all functions which use this lock have a journal head pointer readily available, it makes more sense to remove the lock helper inlines and write out spin_*lock() at all call sites. Fixup all locking comments as well. Suggested-by: Jan Kara Signed-off-by: Thomas Gleixner Signed-off-by: Jan Kara Cc: "Theodore Ts'o" Cc: Mark Fasheh Cc: Joseph Qi Cc: Joel Becker Cc: Jan Kara Cc: linux-ext4@vger.kernel.org Link: https://lore.kernel.org/r/20190809124233.13277-7-jack@suse.cz Signed-off-by: Theodore Ts'o

jbd2: remove jbd2_journal_inode_add_[write|wait]

2019-09-24T22:54:07+00:00

Since ext4/ocfs2 are using jbd2_inode dirty range scoping APIs now, jbd2_journal_inode_add_[write|wait] are not used any more, remove them. Link: http://lkml.kernel.org/r/1562977611-8412-2-git-send-email-joseph.qi@linux.alibaba.com Signed-off-by: Joseph Qi Reviewed-by: Ross Zwisler Acked-by: Changwei Ge Cc: Gang He Cc: Joel Becker Cc: Joseph Qi Cc: Jun Piao Cc: Junxiao Bi Cc: Mark Fasheh Cc: "Theodore Ts'o" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

jbd2: drop declaration of journal_sync_buffer()

2019-06-20T21:32:21+00:00

The journal_sync_buffer() function was never carried over from jbd to jbd2. So get rid of the vestigal declaration of this (non-existent) function. Signed-off-by: Theodore Ts'o Reviewed-by: Darrick J. Wong

jbd2: introduce jbd2_inode dirty range scoping

2019-06-20T21:24:56+00:00

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 Signed-off-by: Theodore Ts'o Reviewed-by: Jan Kara Cc: stable@vger.kernel.org

jbd2: fix some print format mistakes

2019-05-30T19:08:34+00:00

There are some print format mistakes in debug messages. Fix them. Signed-off-by: Gaowei Pu Signed-off-by: Theodore Ts'o Reviewed-by: Jan Kara