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Diffstat (limited to 'Documentation/filesystems/xfs-delayed-logging-design.rst')
| -rw-r--r-- | Documentation/filesystems/xfs-delayed-logging-design.rst | 18 |
1 files changed, 9 insertions, 9 deletions
diff --git a/Documentation/filesystems/xfs-delayed-logging-design.rst b/Documentation/filesystems/xfs-delayed-logging-design.rst index 4ef419f54663..6402ab8e370c 100644 --- a/Documentation/filesystems/xfs-delayed-logging-design.rst +++ b/Documentation/filesystems/xfs-delayed-logging-design.rst @@ -100,7 +100,7 @@ transactions together:: ntp = xfs_trans_dup(tp); xfs_trans_commit(tp); - xfs_log_reserve(ntp); + xfs_trans_reserve(ntp); This results in a series of "rolling transactions" where the inode is locked across the entire chain of transactions. Hence while this series of rolling @@ -191,7 +191,7 @@ transaction rolling mechanism to re-reserve space on every transaction roll. We know from the implementation of the permanent transactions how many transaction rolls are likely for the common modifications that need to be made. -For example, and inode allocation is typically two transactions - one to +For example, an inode allocation is typically two transactions - one to physically allocate a free inode chunk on disk, and another to allocate an inode from an inode chunk that has free inodes in it. Hence for an inode allocation transaction, we might set the reservation log count to a value of 2 to indicate @@ -200,7 +200,7 @@ chain. Each time a permanent transaction rolls, it consumes an entire unit reservation. Hence when the permanent transaction is first allocated, the log space -reservation is increases from a single unit reservation to multiple unit +reservation is increased from a single unit reservation to multiple unit reservations. That multiple is defined by the reservation log count, and this means we can roll the transaction multiple times before we have to re-reserve log space when we roll the transaction. This ensures that the common @@ -259,7 +259,7 @@ the next transaction in the sequeunce, but we have none remaining. We cannot sleep during the transaction commit process waiting for new log space to become available, as we may end up on the end of the FIFO queue and the items we have locked while we sleep could end up pinning the tail of the log before there is -enough free space in the log to fulfil all of the pending reservations and +enough free space in the log to fulfill all of the pending reservations and then wake up transaction commit in progress. To take a new reservation without sleeping requires us to be able to take a @@ -551,14 +551,14 @@ Essentially, this shows that an item that is in the AIL can still be modified and relogged, so any tracking must be separate to the AIL infrastructure. As such, we cannot reuse the AIL list pointers for tracking committed items, nor can we store state in any field that is protected by the AIL lock. Hence the -committed item tracking needs it's own locks, lists and state fields in the log +committed item tracking needs its own locks, lists and state fields in the log item. Similar to the AIL, tracking of committed items is done through a new list called the Committed Item List (CIL). The list tracks log items that have been committed and have formatted memory buffers attached to them. It tracks objects in transaction commit order, so when an object is relogged it is removed from -it's place in the list and re-inserted at the tail. This is entirely arbitrary +its place in the list and re-inserted at the tail. This is entirely arbitrary and done to make it easy for debugging - the last items in the list are the ones that are most recently modified. Ordering of the CIL is not necessary for transactional integrity (as discussed in the next section) so the ordering is @@ -615,7 +615,7 @@ those changes into the current checkpoint context. We then initialise a new context and attach that to the CIL for aggregation of new transactions. This allows us to unlock the CIL immediately after transfer of all the -committed items and effectively allow new transactions to be issued while we +committed items and effectively allows new transactions to be issued while we are formatting the checkpoint into the log. It also allows concurrent checkpoints to be written into the log buffers in the case of log force heavy workloads, just like the existing transaction commit code does. This, however, @@ -884,9 +884,9 @@ pin the object the first time it is inserted into the CIL - if it is already in the CIL during a transaction commit, then we do not pin it again. Because there can be multiple outstanding checkpoint contexts, we can still see elevated pin counts, but as each checkpoint completes the pin count will retain the correct -value according to it's context. +value according to its context. -Just to make matters more slightly more complex, this checkpoint level context +Just to make matters slightly more complex, this checkpoint level context for the pin count means that the pinning of an item must take place under the CIL commit/flush lock. If we pin the object outside this lock, we cannot guarantee which context the pin count is associated with. This is because of |