![Dave Chinner](/assets/img/avatar_default.png)
Filesystems are occasionally being shut down with this error: xfs_trans_ail_delete_bulk: attempting to delete a log item that is not in the AIL. It was diagnosed to be related to the EFI/EFD commit order when the EFI and EFD are in different checkpoints and the EFD is committed before the EFI here: http://oss.sgi.com/archives/xfs/2013-01/msg00082.html The real problem is that a single bit cannot fully describe the states that the EFI/EFD processing can be in. These completion states are: EFI EFI in AIL EFD Result committed/unpinned Yes committed OK committed/pinned No committed Shutdown uncommitted No committed Shutdown Note that the "result" field is what should happen, not what does happen. The current logic is broken and handles the first two cases correctly by luck. That is, the code will free the EFI if the XFS_EFI_COMMITTED bit is *not* set, rather than if it is set. The inverted logic "works" because if both EFI and EFD are committed, then the first __xfs_efi_release() call clears the XFS_EFI_COMMITTED bit, and the second frees the EFI item. Hence as long as xfs_efi_item_committed() has been called, everything appears to be fine. It is the third case where the logic fails - where xfs_efd_item_committed() is called before xfs_efi_item_committed(), and that results in the EFI being freed before it has been committed. That is the bug that triggered the shutdown, and hence keeping track of whether the EFI has been committed or not is insufficient to correctly order the EFI/EFD operations w.r.t. the AIL. What we really want is this: the EFI is always placed into the AIL before the last reference goes away. The only way to guarantee that is that the EFI is not freed until after it has been unpinned *and* the EFD has been committed. That is, restructure the logic so that the only case that can occur is the first case. This can be done easily by replacing the XFS_EFI_COMMITTED with an EFI reference count. The EFI is initialised with it's own count, and that is not released until it is unpinned. However, there is a complication to this method - the high level EFI/EFD code in xfs_bmap_finish() does not hold direct references to the EFI structure, and runs a transaction commit between the EFI and EFD processing. Hence the EFI can be freed even before the EFD is created using such a method. Further, log recovery uses the AIL for tracking EFI/EFDs that need to be recovered, but it uses the AIL *differently* to the EFI transaction commit. Hence log recovery never pins or unpins EFIs, so we can't drop the EFI reference count indirectly to free the EFI. However, this doesn't prevent us from using a reference count here. There is a 1:1 relationship between EFIs and EFDs, so when we initialise the EFI we can take a reference count for the EFD as well. This solves the xfs_bmap_finish() issue - the EFI will never be freed until the EFD is processed. In terms of log recovery, during the committing of the EFD we can look for the XFS_EFI_RECOVERED bit being set and drop the EFI reference as well, thereby ensuring everything works correctly there as well. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Mark Tinguely <tinguely@sgi.com> Signed-off-by: Ben Myers <bpm@sgi.com>
493 lines
13 KiB
C
493 lines
13 KiB
C
/*
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* Copyright (c) 2000-2001,2005 Silicon Graphics, Inc.
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* All Rights Reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it would be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include "xfs.h"
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#include "xfs_fs.h"
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#include "xfs_types.h"
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#include "xfs_log.h"
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#include "xfs_trans.h"
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#include "xfs_buf_item.h"
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#include "xfs_sb.h"
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#include "xfs_ag.h"
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#include "xfs_mount.h"
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#include "xfs_trans_priv.h"
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#include "xfs_extfree_item.h"
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kmem_zone_t *xfs_efi_zone;
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kmem_zone_t *xfs_efd_zone;
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static inline struct xfs_efi_log_item *EFI_ITEM(struct xfs_log_item *lip)
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{
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return container_of(lip, struct xfs_efi_log_item, efi_item);
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}
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void
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xfs_efi_item_free(
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struct xfs_efi_log_item *efip)
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{
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if (efip->efi_format.efi_nextents > XFS_EFI_MAX_FAST_EXTENTS)
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kmem_free(efip);
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else
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kmem_zone_free(xfs_efi_zone, efip);
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}
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/*
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* Freeing the efi requires that we remove it from the AIL if it has already
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* been placed there. However, the EFI may not yet have been placed in the AIL
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* when called by xfs_efi_release() from EFD processing due to the ordering of
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* committed vs unpin operations in bulk insert operations. Hence the reference
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* count to ensure only the last caller frees the EFI.
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*/
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STATIC void
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__xfs_efi_release(
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struct xfs_efi_log_item *efip)
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{
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struct xfs_ail *ailp = efip->efi_item.li_ailp;
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if (atomic_dec_and_test(&efip->efi_refcount)) {
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spin_lock(&ailp->xa_lock);
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/* xfs_trans_ail_delete() drops the AIL lock. */
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xfs_trans_ail_delete(ailp, &efip->efi_item,
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SHUTDOWN_LOG_IO_ERROR);
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xfs_efi_item_free(efip);
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}
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}
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/*
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* This returns the number of iovecs needed to log the given efi item.
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* We only need 1 iovec for an efi item. It just logs the efi_log_format
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* structure.
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*/
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STATIC uint
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xfs_efi_item_size(
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struct xfs_log_item *lip)
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{
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return 1;
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}
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/*
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* This is called to fill in the vector of log iovecs for the
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* given efi log item. We use only 1 iovec, and we point that
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* at the efi_log_format structure embedded in the efi item.
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* It is at this point that we assert that all of the extent
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* slots in the efi item have been filled.
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*/
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STATIC void
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xfs_efi_item_format(
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struct xfs_log_item *lip,
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struct xfs_log_iovec *log_vector)
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{
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struct xfs_efi_log_item *efip = EFI_ITEM(lip);
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uint size;
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ASSERT(atomic_read(&efip->efi_next_extent) ==
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efip->efi_format.efi_nextents);
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efip->efi_format.efi_type = XFS_LI_EFI;
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size = sizeof(xfs_efi_log_format_t);
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size += (efip->efi_format.efi_nextents - 1) * sizeof(xfs_extent_t);
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efip->efi_format.efi_size = 1;
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log_vector->i_addr = &efip->efi_format;
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log_vector->i_len = size;
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log_vector->i_type = XLOG_REG_TYPE_EFI_FORMAT;
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ASSERT(size >= sizeof(xfs_efi_log_format_t));
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}
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/*
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* Pinning has no meaning for an efi item, so just return.
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*/
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STATIC void
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xfs_efi_item_pin(
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struct xfs_log_item *lip)
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{
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}
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/*
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* While EFIs cannot really be pinned, the unpin operation is the last place at
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* which the EFI is manipulated during a transaction. If we are being asked to
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* remove the EFI it's because the transaction has been cancelled and by
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* definition that means the EFI cannot be in the AIL so remove it from the
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* transaction and free it. Otherwise coordinate with xfs_efi_release()
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* to determine who gets to free the EFI.
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*/
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STATIC void
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xfs_efi_item_unpin(
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struct xfs_log_item *lip,
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int remove)
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{
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struct xfs_efi_log_item *efip = EFI_ITEM(lip);
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if (remove) {
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ASSERT(!(lip->li_flags & XFS_LI_IN_AIL));
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if (lip->li_desc)
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xfs_trans_del_item(lip);
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xfs_efi_item_free(efip);
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return;
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}
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__xfs_efi_release(efip);
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}
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/*
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* Efi items have no locking or pushing. However, since EFIs are pulled from
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* the AIL when their corresponding EFDs are committed to disk, their situation
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* is very similar to being pinned. Return XFS_ITEM_PINNED so that the caller
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* will eventually flush the log. This should help in getting the EFI out of
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* the AIL.
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*/
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STATIC uint
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xfs_efi_item_push(
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struct xfs_log_item *lip,
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struct list_head *buffer_list)
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{
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return XFS_ITEM_PINNED;
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}
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STATIC void
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xfs_efi_item_unlock(
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struct xfs_log_item *lip)
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{
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if (lip->li_flags & XFS_LI_ABORTED)
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xfs_efi_item_free(EFI_ITEM(lip));
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}
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/*
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* The EFI is logged only once and cannot be moved in the log, so simply return
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* the lsn at which it's been logged.
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*/
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STATIC xfs_lsn_t
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xfs_efi_item_committed(
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struct xfs_log_item *lip,
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xfs_lsn_t lsn)
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{
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return lsn;
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}
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/*
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* The EFI dependency tracking op doesn't do squat. It can't because
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* it doesn't know where the free extent is coming from. The dependency
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* tracking has to be handled by the "enclosing" metadata object. For
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* example, for inodes, the inode is locked throughout the extent freeing
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* so the dependency should be recorded there.
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*/
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STATIC void
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xfs_efi_item_committing(
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struct xfs_log_item *lip,
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xfs_lsn_t lsn)
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{
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}
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/*
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* This is the ops vector shared by all efi log items.
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*/
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static const struct xfs_item_ops xfs_efi_item_ops = {
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.iop_size = xfs_efi_item_size,
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.iop_format = xfs_efi_item_format,
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.iop_pin = xfs_efi_item_pin,
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.iop_unpin = xfs_efi_item_unpin,
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.iop_unlock = xfs_efi_item_unlock,
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.iop_committed = xfs_efi_item_committed,
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.iop_push = xfs_efi_item_push,
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.iop_committing = xfs_efi_item_committing
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};
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/*
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* Allocate and initialize an efi item with the given number of extents.
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*/
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struct xfs_efi_log_item *
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xfs_efi_init(
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struct xfs_mount *mp,
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uint nextents)
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{
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struct xfs_efi_log_item *efip;
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uint size;
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ASSERT(nextents > 0);
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if (nextents > XFS_EFI_MAX_FAST_EXTENTS) {
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size = (uint)(sizeof(xfs_efi_log_item_t) +
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((nextents - 1) * sizeof(xfs_extent_t)));
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efip = kmem_zalloc(size, KM_SLEEP);
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} else {
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efip = kmem_zone_zalloc(xfs_efi_zone, KM_SLEEP);
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}
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xfs_log_item_init(mp, &efip->efi_item, XFS_LI_EFI, &xfs_efi_item_ops);
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efip->efi_format.efi_nextents = nextents;
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efip->efi_format.efi_id = (__psint_t)(void*)efip;
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atomic_set(&efip->efi_next_extent, 0);
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atomic_set(&efip->efi_refcount, 2);
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return efip;
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}
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/*
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* Copy an EFI format buffer from the given buf, and into the destination
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* EFI format structure.
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* The given buffer can be in 32 bit or 64 bit form (which has different padding),
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* one of which will be the native format for this kernel.
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* It will handle the conversion of formats if necessary.
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*/
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int
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xfs_efi_copy_format(xfs_log_iovec_t *buf, xfs_efi_log_format_t *dst_efi_fmt)
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{
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xfs_efi_log_format_t *src_efi_fmt = buf->i_addr;
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uint i;
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uint len = sizeof(xfs_efi_log_format_t) +
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(src_efi_fmt->efi_nextents - 1) * sizeof(xfs_extent_t);
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uint len32 = sizeof(xfs_efi_log_format_32_t) +
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(src_efi_fmt->efi_nextents - 1) * sizeof(xfs_extent_32_t);
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uint len64 = sizeof(xfs_efi_log_format_64_t) +
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(src_efi_fmt->efi_nextents - 1) * sizeof(xfs_extent_64_t);
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if (buf->i_len == len) {
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memcpy((char *)dst_efi_fmt, (char*)src_efi_fmt, len);
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return 0;
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} else if (buf->i_len == len32) {
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xfs_efi_log_format_32_t *src_efi_fmt_32 = buf->i_addr;
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dst_efi_fmt->efi_type = src_efi_fmt_32->efi_type;
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dst_efi_fmt->efi_size = src_efi_fmt_32->efi_size;
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dst_efi_fmt->efi_nextents = src_efi_fmt_32->efi_nextents;
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dst_efi_fmt->efi_id = src_efi_fmt_32->efi_id;
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for (i = 0; i < dst_efi_fmt->efi_nextents; i++) {
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dst_efi_fmt->efi_extents[i].ext_start =
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src_efi_fmt_32->efi_extents[i].ext_start;
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dst_efi_fmt->efi_extents[i].ext_len =
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src_efi_fmt_32->efi_extents[i].ext_len;
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}
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return 0;
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} else if (buf->i_len == len64) {
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xfs_efi_log_format_64_t *src_efi_fmt_64 = buf->i_addr;
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dst_efi_fmt->efi_type = src_efi_fmt_64->efi_type;
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dst_efi_fmt->efi_size = src_efi_fmt_64->efi_size;
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dst_efi_fmt->efi_nextents = src_efi_fmt_64->efi_nextents;
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dst_efi_fmt->efi_id = src_efi_fmt_64->efi_id;
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for (i = 0; i < dst_efi_fmt->efi_nextents; i++) {
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dst_efi_fmt->efi_extents[i].ext_start =
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src_efi_fmt_64->efi_extents[i].ext_start;
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dst_efi_fmt->efi_extents[i].ext_len =
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src_efi_fmt_64->efi_extents[i].ext_len;
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}
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return 0;
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}
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return EFSCORRUPTED;
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}
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/*
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* This is called by the efd item code below to release references to the given
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* efi item. Each efd calls this with the number of extents that it has
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* logged, and when the sum of these reaches the total number of extents logged
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* by this efi item we can free the efi item.
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*/
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void
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xfs_efi_release(xfs_efi_log_item_t *efip,
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uint nextents)
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{
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ASSERT(atomic_read(&efip->efi_next_extent) >= nextents);
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if (atomic_sub_and_test(nextents, &efip->efi_next_extent)) {
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__xfs_efi_release(efip);
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/* recovery needs us to drop the EFI reference, too */
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if (test_bit(XFS_EFI_RECOVERED, &efip->efi_flags))
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__xfs_efi_release(efip);
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}
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}
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static inline struct xfs_efd_log_item *EFD_ITEM(struct xfs_log_item *lip)
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{
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return container_of(lip, struct xfs_efd_log_item, efd_item);
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}
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STATIC void
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xfs_efd_item_free(struct xfs_efd_log_item *efdp)
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{
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if (efdp->efd_format.efd_nextents > XFS_EFD_MAX_FAST_EXTENTS)
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kmem_free(efdp);
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else
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kmem_zone_free(xfs_efd_zone, efdp);
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}
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/*
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* This returns the number of iovecs needed to log the given efd item.
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* We only need 1 iovec for an efd item. It just logs the efd_log_format
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* structure.
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*/
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STATIC uint
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xfs_efd_item_size(
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struct xfs_log_item *lip)
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{
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return 1;
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}
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/*
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* This is called to fill in the vector of log iovecs for the
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* given efd log item. We use only 1 iovec, and we point that
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* at the efd_log_format structure embedded in the efd item.
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* It is at this point that we assert that all of the extent
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* slots in the efd item have been filled.
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*/
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STATIC void
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xfs_efd_item_format(
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struct xfs_log_item *lip,
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struct xfs_log_iovec *log_vector)
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{
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struct xfs_efd_log_item *efdp = EFD_ITEM(lip);
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uint size;
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ASSERT(efdp->efd_next_extent == efdp->efd_format.efd_nextents);
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efdp->efd_format.efd_type = XFS_LI_EFD;
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size = sizeof(xfs_efd_log_format_t);
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size += (efdp->efd_format.efd_nextents - 1) * sizeof(xfs_extent_t);
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efdp->efd_format.efd_size = 1;
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log_vector->i_addr = &efdp->efd_format;
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log_vector->i_len = size;
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log_vector->i_type = XLOG_REG_TYPE_EFD_FORMAT;
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ASSERT(size >= sizeof(xfs_efd_log_format_t));
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}
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/*
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* Pinning has no meaning for an efd item, so just return.
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*/
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STATIC void
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xfs_efd_item_pin(
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struct xfs_log_item *lip)
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{
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}
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/*
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* Since pinning has no meaning for an efd item, unpinning does
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* not either.
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*/
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STATIC void
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xfs_efd_item_unpin(
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struct xfs_log_item *lip,
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int remove)
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{
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}
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/*
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* There isn't much you can do to push on an efd item. It is simply stuck
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* waiting for the log to be flushed to disk.
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*/
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STATIC uint
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xfs_efd_item_push(
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struct xfs_log_item *lip,
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struct list_head *buffer_list)
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{
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return XFS_ITEM_PINNED;
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}
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STATIC void
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xfs_efd_item_unlock(
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struct xfs_log_item *lip)
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{
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if (lip->li_flags & XFS_LI_ABORTED)
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xfs_efd_item_free(EFD_ITEM(lip));
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}
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/*
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* When the efd item is committed to disk, all we need to do
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* is delete our reference to our partner efi item and then
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* free ourselves. Since we're freeing ourselves we must
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* return -1 to keep the transaction code from further referencing
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* this item.
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*/
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STATIC xfs_lsn_t
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xfs_efd_item_committed(
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struct xfs_log_item *lip,
|
|
xfs_lsn_t lsn)
|
|
{
|
|
struct xfs_efd_log_item *efdp = EFD_ITEM(lip);
|
|
|
|
/*
|
|
* If we got a log I/O error, it's always the case that the LR with the
|
|
* EFI got unpinned and freed before the EFD got aborted.
|
|
*/
|
|
if (!(lip->li_flags & XFS_LI_ABORTED))
|
|
xfs_efi_release(efdp->efd_efip, efdp->efd_format.efd_nextents);
|
|
|
|
xfs_efd_item_free(efdp);
|
|
return (xfs_lsn_t)-1;
|
|
}
|
|
|
|
/*
|
|
* The EFD dependency tracking op doesn't do squat. It can't because
|
|
* it doesn't know where the free extent is coming from. The dependency
|
|
* tracking has to be handled by the "enclosing" metadata object. For
|
|
* example, for inodes, the inode is locked throughout the extent freeing
|
|
* so the dependency should be recorded there.
|
|
*/
|
|
STATIC void
|
|
xfs_efd_item_committing(
|
|
struct xfs_log_item *lip,
|
|
xfs_lsn_t lsn)
|
|
{
|
|
}
|
|
|
|
/*
|
|
* This is the ops vector shared by all efd log items.
|
|
*/
|
|
static const struct xfs_item_ops xfs_efd_item_ops = {
|
|
.iop_size = xfs_efd_item_size,
|
|
.iop_format = xfs_efd_item_format,
|
|
.iop_pin = xfs_efd_item_pin,
|
|
.iop_unpin = xfs_efd_item_unpin,
|
|
.iop_unlock = xfs_efd_item_unlock,
|
|
.iop_committed = xfs_efd_item_committed,
|
|
.iop_push = xfs_efd_item_push,
|
|
.iop_committing = xfs_efd_item_committing
|
|
};
|
|
|
|
/*
|
|
* Allocate and initialize an efd item with the given number of extents.
|
|
*/
|
|
struct xfs_efd_log_item *
|
|
xfs_efd_init(
|
|
struct xfs_mount *mp,
|
|
struct xfs_efi_log_item *efip,
|
|
uint nextents)
|
|
|
|
{
|
|
struct xfs_efd_log_item *efdp;
|
|
uint size;
|
|
|
|
ASSERT(nextents > 0);
|
|
if (nextents > XFS_EFD_MAX_FAST_EXTENTS) {
|
|
size = (uint)(sizeof(xfs_efd_log_item_t) +
|
|
((nextents - 1) * sizeof(xfs_extent_t)));
|
|
efdp = kmem_zalloc(size, KM_SLEEP);
|
|
} else {
|
|
efdp = kmem_zone_zalloc(xfs_efd_zone, KM_SLEEP);
|
|
}
|
|
|
|
xfs_log_item_init(mp, &efdp->efd_item, XFS_LI_EFD, &xfs_efd_item_ops);
|
|
efdp->efd_efip = efip;
|
|
efdp->efd_format.efd_nextents = nextents;
|
|
efdp->efd_format.efd_efi_id = efip->efi_format.efi_id;
|
|
|
|
return efdp;
|
|
}
|