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114 lines
2.9 KiB
114 lines
2.9 KiB
/* SPDX-License-Identifier: GPL-2.0 */ |
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/* |
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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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#include <linux/spinlock.h> |
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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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* Protect the buffer head state |
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*/ |
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spinlock_t b_state_lock; |
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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 [b_state_lock] |
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* NOTE: We *cannot* combine this with b_modified into a bitfield |
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* as gcc would then (which the C standard allows but which is |
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* very unuseful) make 64-bit accesses to the bitfield and clobber |
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* b_jcount if its update races with bitfield modification. |
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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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* [b_state_lock] |
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*/ |
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unsigned b_modified; |
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/* |
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* Copy of the buffer data frozen for writing to the log. |
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* [b_state_lock] |
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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. [b_state_lock] |
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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] [b_state_lock] |
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* Either of these locks is enough for reading, both are needed for |
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* changes. |
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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] [b_state_lock] |
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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] [b_state_lock] |
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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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