1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (c) 2000,2005 Silicon Graphics, Inc.
4  * All Rights Reserved.
5  */
6 #ifndef	__XFS_EXTFREE_ITEM_H__
7 #define	__XFS_EXTFREE_ITEM_H__
8 
9 /* kernel only EFI/EFD definitions */
10 
11 struct xfs_mount;
12 struct kmem_cache;
13 
14 /*
15  * Max number of extents in fast allocation path.
16  */
17 #define	XFS_EFI_MAX_FAST_EXTENTS	16
18 
19 /*
20  * This is the "extent free intention" log item.  It is used to log the fact
21  * that some extents need to be free.  It is used in conjunction with the
22  * "extent free done" log item described below.
23  *
24  * The EFI is reference counted so that it is not freed prior to both the EFI
25  * and EFD being committed and unpinned. This ensures the EFI is inserted into
26  * the AIL even in the event of out of order EFI/EFD processing. In other words,
27  * an EFI is born with two references:
28  *
29  * 	1.) an EFI held reference to track EFI AIL insertion
30  * 	2.) an EFD held reference to track EFD commit
31  *
32  * On allocation, both references are the responsibility of the caller. Once the
33  * EFI is added to and dirtied in a transaction, ownership of reference one
34  * transfers to the transaction. The reference is dropped once the EFI is
35  * inserted to the AIL or in the event of failure along the way (e.g., commit
36  * failure, log I/O error, etc.). Note that the caller remains responsible for
37  * the EFD reference under all circumstances to this point. The caller has no
38  * means to detect failure once the transaction is committed, however.
39  * Therefore, an EFD is required after this point, even in the event of
40  * unrelated failure.
41  *
42  * Once an EFD is allocated and dirtied in a transaction, reference two
43  * transfers to the transaction. The EFD reference is dropped once it reaches
44  * the unpin handler. Similar to the EFI, the reference also drops in the event
45  * of commit failure or log I/O errors. Note that the EFD is not inserted in the
46  * AIL, so at this point both the EFI and EFD are freed.
47  */
48 struct xfs_efi_log_item {
49 	struct xfs_log_item	efi_item;
50 	atomic_t		efi_refcount;
51 	atomic_t		efi_next_extent;
52 	xfs_efi_log_format_t	efi_format;
53 };
54 
55 static inline size_t
xfs_efi_log_item_sizeof(unsigned int nr)56 xfs_efi_log_item_sizeof(
57 	unsigned int		nr)
58 {
59 	return offsetof(struct xfs_efi_log_item, efi_format) +
60 			xfs_efi_log_format_sizeof(nr);
61 }
62 
63 /*
64  * This is the "extent free done" log item.  It is used to log
65  * the fact that some extents earlier mentioned in an efi item
66  * have been freed.
67  */
68 struct xfs_efd_log_item {
69 	struct xfs_log_item	efd_item;
70 	struct xfs_efi_log_item *efd_efip;
71 	uint			efd_next_extent;
72 	xfs_efd_log_format_t	efd_format;
73 };
74 
75 static inline size_t
xfs_efd_log_item_sizeof(unsigned int nr)76 xfs_efd_log_item_sizeof(
77 	unsigned int		nr)
78 {
79 	return offsetof(struct xfs_efd_log_item, efd_format) +
80 			xfs_efd_log_format_sizeof(nr);
81 }
82 
83 /*
84  * Max number of extents in fast allocation path.
85  */
86 #define	XFS_EFD_MAX_FAST_EXTENTS	16
87 
88 extern struct kmem_cache	*xfs_efi_cache;
89 extern struct kmem_cache	*xfs_efd_cache;
90 
91 #endif	/* __XFS_EXTFREE_ITEM_H__ */
92