fs/xfs/xfs_extfree_item.h

   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_zone;
  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 /*
  56  * This is the "extent free done" log item.  It is used to log
  57  * the fact that some extents earlier mentioned in an efi item
  58  * have been freed.
  59  */
  60 struct xfs_efd_log_item {
  61         struct xfs_log_item     efd_item;
  62         struct xfs_efi_log_item *efd_efip;
  63         uint                    efd_next_extent;
  64         xfs_efd_log_format_t    efd_format;
  65 };
  66
  67 /*
  68  * Max number of extents in fast allocation path.
  69  */
  70 #define XFS_EFD_MAX_FAST_EXTENTS        16
  71
  72 extern struct kmem_zone *xfs_efi_zone;
  73 extern struct kmem_zone *xfs_efd_zone;
  74
  75 #endif  /* __XFS_EXTFREE_ITEM_H__ */