fs/xfs/xfs_extfree_item.h

   1 /*
   2  * Copyright (c) 2000,2005 Silicon Graphics, Inc.
   3  * All Rights Reserved.
   4  *
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU General Public License as
   7  * published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it would be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write the Free Software Foundation,
  16  * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  17  */
  18 #ifndef __XFS_EXTFREE_ITEM_H__
  19 #define __XFS_EXTFREE_ITEM_H__
  20
  21 /* kernel only EFI/EFD definitions */
  22
  23 struct xfs_mount;
  24 struct kmem_zone;
  25
  26 /*
  27  * Max number of extents in fast allocation path.
  28  */
  29 #define XFS_EFI_MAX_FAST_EXTENTS        16
  30
  31 /*
  32  * Define EFI flag bits. Manipulated by set/clear/test_bit operators.
  33  */
  34 #define XFS_EFI_RECOVERED       1
  35
  36 /*
  37  * This is the "extent free intention" log item.  It is used to log the fact
  38  * that some extents need to be free.  It is used in conjunction with the
  39  * "extent free done" log item described below.
  40  *
  41  * The EFI is reference counted so that it is not freed prior to both the EFI
  42  * and EFD being committed and unpinned. This ensures the EFI is inserted into
  43  * the AIL even in the event of out of order EFI/EFD processing. In other words,
  44  * an EFI is born with two references:
  45  *
  46  *      1.) an EFI held reference to track EFI AIL insertion
  47  *      2.) an EFD held reference to track EFD commit
  48  *
  49  * On allocation, both references are the responsibility of the caller. Once the
  50  * EFI is added to and dirtied in a transaction, ownership of reference one
  51  * transfers to the transaction. The reference is dropped once the EFI is
  52  * inserted to the AIL or in the event of failure along the way (e.g., commit
  53  * failure, log I/O error, etc.). Note that the caller remains responsible for
  54  * the EFD reference under all circumstances to this point. The caller has no
  55  * means to detect failure once the transaction is committed, however.
  56  * Therefore, an EFD is required after this point, even in the event of
  57  * unrelated failure.
  58  *
  59  * Once an EFD is allocated and dirtied in a transaction, reference two
  60  * transfers to the transaction. The EFD reference is dropped once it reaches
  61  * the unpin handler. Similar to the EFI, the reference also drops in the event
  62  * of commit failure or log I/O errors. Note that the EFD is not inserted in the
  63  * AIL, so at this point both the EFI and EFD are freed.
  64  */
  65 typedef struct xfs_efi_log_item {
  66         xfs_log_item_t          efi_item;
  67         atomic_t                efi_refcount;
  68         atomic_t                efi_next_extent;
  69         unsigned long           efi_flags;      /* misc flags */
  70         xfs_efi_log_format_t    efi_format;
  71 } xfs_efi_log_item_t;
  72
  73 /*
  74  * This is the "extent free done" log item.  It is used to log
  75  * the fact that some extents earlier mentioned in an efi item
  76  * have been freed.
  77  */
  78 typedef struct xfs_efd_log_item {
  79         xfs_log_item_t          efd_item;
  80         xfs_efi_log_item_t      *efd_efip;
  81         uint                    efd_next_extent;
  82         xfs_efd_log_format_t    efd_format;
  83 } xfs_efd_log_item_t;
  84
  85 /*
  86  * Max number of extents in fast allocation path.
  87  */
  88 #define XFS_EFD_MAX_FAST_EXTENTS        16
  89
  90 extern struct kmem_zone *xfs_efi_zone;
  91 extern struct kmem_zone *xfs_efd_zone;
  92
  93 xfs_efi_log_item_t      *xfs_efi_init(struct xfs_mount *, uint);
  94 xfs_efd_log_item_t      *xfs_efd_init(struct xfs_mount *, xfs_efi_log_item_t *,
  95                                       uint);
  96 int                     xfs_efi_copy_format(xfs_log_iovec_t *buf,
  97                                             xfs_efi_log_format_t *dst_efi_fmt);
  98 void                    xfs_efi_item_free(xfs_efi_log_item_t *);
  99 void                    xfs_efi_release(struct xfs_efi_log_item *);
 100
 101 #endif  /* __XFS_EXTFREE_ITEM_H__ */