kernel.git/fs/gfs2/trans.c, branch linux-6.7.y

gfs2: Fix freeze consistency check in gfs2_trans_add_meta

2023-08-07T16:40:51Z

Function gfs2_trans_add_meta() checks for the SDF_FROZEN flag to make sure that no buffers are added to a transaction while the filesystem is frozen. With the recent freeze/thaw rework, the SDF_FROZEN flag is cleared after thaw_super() is called, which is sufficient for serializing freeze/thaw. However, other filesystem operations started after thaw_super() may now be calling gfs2_trans_add_meta() before the SDF_FROZEN flag is cleared, which will trigger the SDF_FROZEN check in gfs2_trans_add_meta(). Fix that by checking the s_writers.frozen state instead. In addition, make sure not to call gfs2_assert_withdraw() with the sd_log_lock spin lock held. Check for a withdrawn filesystem before checking for a frozen filesystem, and don't pin/add buffers to the current transaction in case of a failure in either case. Signed-off-by: Andreas Gruenbacher Signed-off-by: Bob Peterson

gfs2: Replace sd_freeze_state with SDF_FROZEN flag

2023-07-03T20:30:23Z

Replace sd_freeze_state with a new SDF_FROZEN flag. There no longer is a need for indicating that a freeze is in progress (SDF_STARTING_FREEZE); we are now protecting the critical sections with the sd_freeze_mutex. Signed-off-by: Andreas Gruenbacher

gfs2: fix use-after-free in trans_drain

2021-03-07T16:04:55Z

This patch adds code to function trans_drain to remove drained bd elements from the ail lists, if queued, before freeing the bd. If we don't remove the bd from the ail, function ail_drain will try to reference the bd after it has been freed by trans_drain. Thanks to Andy Price for his analysis of the problem. Reported-by: Andy Price Signed-off-by: Bob Peterson Signed-off-by: Andreas Gruenbacher

gfs2: Per-revoke accounting in transactions

2021-02-22T20:16:23Z

In the log, revokes are stored as a revoke descriptor (struct gfs2_log_descriptor), followed by zero or more additional revoke blocks (struct gfs2_meta_header). On filesystems with a blocksize of 4k, the revoke descriptor contains up to 503 revokes, and the metadata blocks contain up to 509 revokes each. We've so far been reserving space for revokes in transactions in block granularity, so a lot more space than necessary was being allocated and then released again. This patch switches to assigning revokes to transactions individually instead. Initially, space for the revoke descriptor is reserved and handed out to transactions. When more revokes than that are reserved, additional revoke blocks are added. When the log is flushed, the space for the additional revoke blocks is released, but we keep the space for the revoke descriptor block allocated. Transactions may still reserve more revokes than they will actually need in the end, but now we won't overshoot the target as much, and by only returning the space for excess revokes at log flush time, we further reduce the amount of contention between processes. Signed-off-by: Andreas Gruenbacher

gfs2: Rework the log space allocation logic

2021-02-22T20:16:22Z

The current log space allocation logic is hard to understand or extend. The principle it that when the log is flushed, we may or may not have a transaction active that has space allocated in the log. To deal with that, we set aside a magical number of blocks to be used in case we don't have an active transaction. It isn't clear that the pool will always be big enough. In addition, we can't return unused log space at the end of a transaction, so the number of blocks allocated must exactly match the number of blocks used. Simplify this as follows: * When transactions are allocated or merged, always reserve enough blocks to flush the transaction (err on the safe side). * In gfs2_log_flush, return any allocated blocks that haven't been used. * Maintain a pool of spare blocks big enough to do one log flush, as before. * In gfs2_log_flush, when we have no active transaction, allocate a suitable number of blocks. For that, use the spare pool when called from logd, and leave the pool alone otherwise. This means that when the log is almost full, logd will still be able to do one more log flush, which will result in more log space becoming available. This will make the log space allocator code easier to work with in the future. Signed-off-by: Andreas Gruenbacher

gfs2: Use a tighter bound in gfs2_trans_begin

2021-02-03T17:37:25Z

Use a tighter bound for the number of blocks required by transactions in gfs2_trans_begin: in the worst case, we'll have mixed data and metadata, so we'll need a log desciptor for each type. Signed-off-by: Andreas Gruenbacher

gfs2: Clean up gfs2_log_reserve

2021-02-03T17:37:24Z

Wake up log waiters in gfs2_log_release when log space has actually become available. This is a much better place for the wakeup than gfs2_logd. Check if enough log space is immeditely available before anything else. If there isn't, use io_wait_event to wait instead of open-coding it. Signed-off-by: Andreas Gruenbacher

gfs2: Move lock flush locking to gfs2_trans_{begin,end}

2021-02-03T17:37:24Z

Move the read locking of sd_log_flush_lock from gfs2_log_reserve to gfs2_trans_begin, and its unlocking from gfs2_log_release to gfs2_trans_end. Use gfs2_log_release in two places in which it was open coded before. Signed-off-by: Andreas Gruenbacher

gfs2: Get rid of sd_reserving_log

2021-02-03T17:37:24Z

This counter and the associated wait queue are only used so that gfs2_make_fs_ro can efficiently wait for all pending log space allocations to fail after setting the filesystem to read-only. This comes at the cost of waking up that wait queue very frequently. Instead, when gfs2_log_reserve fails because the filesystem has become read-only, Wake up sd_log_waitq. In gfs2_make_fs_ro, set the file system read-only and then wait until all the log space has been released. Give up and report the problem after a while. With that, sd_reserving_log and sd_reserving_log_wait can be removed. Signed-off-by: Andreas Gruenbacher

gfs2: Clean up on-stack transactions

2021-02-03T17:37:10Z

Replace the TR_ALLOCED flag by its inverse, TR_ONSTACK: that way, the flag only needs to be set in the exceptional case of on-stack transactions. Split off __gfs2_trans_begin from gfs2_trans_begin and use it to replace the open-coded version in gfs2_ail_empty_gl. Signed-off-by: Andreas Gruenbacher