c2cc7028e4
The b_cow_tid field will be used by the ext4 snapshots code to store the transaction id when the buffer was last cowed. Merging this patch to mainline will allow users to test ext4 snapshots as a standalone module, without the need to patch and install a development kernel. On 64bit machines this field uses fills in a padding "hole" and does not increase the size of the struct. On a 32bit machine this patch increases the size of the struct from 60 to 64 bytes. Signed-off-by: Amir Goldstein <amir73il@users.sf.net> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
108 lines
2.6 KiB
C
108 lines
2.6 KiB
C
/*
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* include/linux/journal-head.h
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*
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* buffer_head fields for JBD
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*
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* 27 May 2001 Andrew Morton
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* Created - pulled out of fs.h
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*/
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#ifndef JOURNAL_HEAD_H_INCLUDED
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#define JOURNAL_HEAD_H_INCLUDED
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typedef unsigned int tid_t; /* Unique transaction ID */
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typedef struct transaction_s transaction_t; /* Compound transaction type */
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struct buffer_head;
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struct journal_head {
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/*
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* Points back to our buffer_head. [jbd_lock_bh_journal_head()]
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*/
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struct buffer_head *b_bh;
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/*
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* Reference count - see description in journal.c
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* [jbd_lock_bh_journal_head()]
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*/
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int b_jcount;
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/*
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* Journalling list for this buffer [jbd_lock_bh_state()]
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*/
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unsigned b_jlist;
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/*
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* This flag signals the buffer has been modified by
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* the currently running transaction
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* [jbd_lock_bh_state()]
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*/
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unsigned b_modified;
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/*
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* This feild tracks the last transaction id in which this buffer
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* has been cowed
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* [jbd_lock_bh_state()]
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*/
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unsigned b_cow_tid;
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/*
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* Copy of the buffer data frozen for writing to the log.
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* [jbd_lock_bh_state()]
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*/
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char *b_frozen_data;
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/*
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* Pointer to a saved copy of the buffer containing no uncommitted
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* deallocation references, so that allocations can avoid overwriting
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* uncommitted deletes. [jbd_lock_bh_state()]
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*/
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char *b_committed_data;
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/*
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* Pointer to the compound transaction which owns this buffer's
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* metadata: either the running transaction or the committing
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* transaction (if there is one). Only applies to buffers on a
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* transaction's data or metadata journaling list.
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* [j_list_lock] [jbd_lock_bh_state()]
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*/
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transaction_t *b_transaction;
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/*
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* Pointer to the running compound transaction which is currently
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* modifying the buffer's metadata, if there was already a transaction
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* committing it when the new transaction touched it.
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* [t_list_lock] [jbd_lock_bh_state()]
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*/
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transaction_t *b_next_transaction;
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/*
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* Doubly-linked list of buffers on a transaction's data, metadata or
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* forget queue. [t_list_lock] [jbd_lock_bh_state()]
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*/
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struct journal_head *b_tnext, *b_tprev;
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/*
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* Pointer to the compound transaction against which this buffer
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* is checkpointed. Only dirty buffers can be checkpointed.
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* [j_list_lock]
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*/
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transaction_t *b_cp_transaction;
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/*
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* Doubly-linked list of buffers still remaining to be flushed
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* before an old transaction can be checkpointed.
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* [j_list_lock]
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*/
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struct journal_head *b_cpnext, *b_cpprev;
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/* Trigger type */
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struct jbd2_buffer_trigger_type *b_triggers;
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/* Trigger type for the committing transaction's frozen data */
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struct jbd2_buffer_trigger_type *b_frozen_triggers;
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};
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#endif /* JOURNAL_HEAD_H_INCLUDED */
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