- 根目录:
- fs
- xfs
- xfs_buf_item.c
/*
* Copyright (c) 2000-2005 Silicon Graphics, Inc.
* All Rights Reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it would be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_format.h"
#include "xfs_log_format.h"
#include "xfs_trans_resv.h"
#include "xfs_bit.h"
#include "xfs_sb.h"
#include "xfs_mount.h"
#include "xfs_trans.h"
#include "xfs_buf_item.h"
#include "xfs_trans_priv.h"
#include "xfs_error.h"
#include "xfs_trace.h"
#include "xfs_log.h"
kmem_zone_t *xfs_buf_item_zone;
static inline struct xfs_buf_log_item *BUF_ITEM(struct xfs_log_item *lip)
{
return container_of(lip, struct xfs_buf_log_item, bli_item);
}
STATIC void xfs_buf_do_callbacks(struct xfs_buf *bp);
static inline int
xfs_buf_log_format_size(
struct xfs_buf_log_format *blfp)
{
return offsetof(struct xfs_buf_log_format, blf_data_map) +
(blfp->blf_map_size * sizeof(blfp->blf_data_map[0]));
}
/*
* This returns the number of log iovecs needed to log the
* given buf log item.
*
* It calculates this as 1 iovec for the buf log format structure
* and 1 for each stretch of non-contiguous chunks to be logged.
* Contiguous chunks are logged in a single iovec.
*
* If the XFS_BLI_STALE flag has been set, then log nothing.
*/
STATIC void
xfs_buf_item_size_segment(
struct xfs_buf_log_item *bip,
struct xfs_buf_log_format *blfp,
int *nvecs,
int *nbytes)
{
struct xfs_buf *bp = bip->bli_buf;
int next_bit;
int last_bit;
last_bit = xfs_next_bit(blfp->blf_data_map, blfp->blf_map_size, 0);
if (last_bit == -1)
return;
/*
* initial count for a dirty buffer is 2 vectors - the format structure
* and the first dirty region.
*/
*nvecs += 2;
*nbytes += xfs_buf_log_format_size(blfp) + XFS_BLF_CHUNK;
while (last_bit != -1) {
/*
* This takes the bit number to start looking from and
* returns the next set bit from there. It returns -1
* if there are no more bits set or the start bit is
* beyond the end of the bitmap.
*/
next_bit = xfs_next_bit(blfp->blf_data_map, blfp->blf_map_size,
last_bit + 1);
/*
* If we run out of bits, leave the loop,
* else if we find a new set of bits bump the number of vecs,
* else keep scanning the current set of bits.
*/
if (next_bit == -1) {
break;
} else if (next_bit != last_bit + 1) {
last_bit = next_bit;
(*nvecs)++;
} else if (xfs_buf_offset(bp, next_bit * XFS_BLF_CHUNK) !=
(xfs_buf_offset(bp, last_bit * XFS_BLF_CHUNK) +
XFS_BLF_CHUNK)) {
last_bit = next_bit;
(*nvecs)++;
} else {
last_bit++;
}
*nbytes += XFS_BLF_CHUNK;
}
}
/*
* This returns the number of log iovecs needed to log the given buf log item.
*
* It calculates this as 1 iovec for the buf log format structure and 1 for each
* stretch of non-contiguous chunks to be logged. Contiguous chunks are logged
* in a single iovec.
*
* Discontiguous buffers need a format structure per region that that is being
* logged. This makes the changes in the buffer appear to log recovery as though
* they came from separate buffers, just like would occur if multiple buffers
* were used instead of a single discontiguous buffer. This enables
* discontiguous buffers to be in-memory constructs, completely transparent to
* what ends up on disk.
*
* If the XFS_BLI_STALE flag has been set, then log nothing but the buf log
* format structures.
*/
STATIC void
xfs_buf_item_size(
struct xfs_log_item *lip,
int *nvecs,
int *nbytes)
{
struct xfs_buf_log_item *bip = BUF_ITEM(lip);
int i;
ASSERT(atomic_read(&bip->bli_refcount) > 0);
if (bip->bli_flags & XFS_BLI_STALE) {
/*
* The buffer is stale, so all we need to log
* is the buf log format structure with the
* cancel flag in it.
*/
trace_xfs_buf_item_size_stale(bip);
ASSERT(bip->__bli_format.blf_flags & XFS_BLF_CANCEL);
*nvecs += bip->bli_format_count;
for (i = 0; i < bip->bli_format_count; i++) {
*nbytes += xfs_buf_log_format_size(&bip->bli_formats[i]);
}
return;
}
ASSERT(bip->bli_flags & XFS_BLI_LOGGED);
if (bip->bli_flags & XFS_BLI_ORDERED) {
/*
* The buffer has been logged just to order it.
* It is not being included in the transaction
* commit, so no vectors are used at all.
*/
trace_xfs_buf_item_size_ordered(bip);
*nvecs = XFS_LOG_VEC_ORDERED;
return;
}
/*
* the vector count is based on the number of buffer vectors we have
* dirty bits in. This will only be greater than one when we have a
* compound buffer with more than one segment dirty. Hence for compound
* buffers we need to track which segment the dirty bits correspond to,
* and when we move from one segment to the next increment the vector
* count for the extra buf log format structure that will need to be
* written.
*/
for (i = 0; i < bip->bli_format_count; i++) {
xfs_buf_item_size_segment(bip, &bip->bli_formats[i],
nvecs, nbytes);
}
trace_xfs_buf_item_size(bip);
}
static inline void
xfs_buf_item_copy_iovec(
struct xfs_log_vec *lv,
struct xfs_log_iovec **vecp,
struct xfs_buf *bp,
uint offset,
int first_bit,
uint nbits)
{
offset += first_bit * XFS_BLF_CHUNK;
xlog_copy_iovec(lv, vecp, XLOG_REG_TYPE_BCHUNK,
xfs_buf_offset(bp, offset),
nbits * XFS_BLF_CHUNK);
}
static inline bool
xfs_buf_item_straddle(
struct xfs_buf *bp,
uint offset,
int next_bit,
int last_bit)
{
return xfs_buf_offset(bp, offset + (next_bit << XFS_BLF_SHIFT)) !=
(xfs_buf_offset(bp, offset + (last_bit << XFS_BLF_SHIFT)) +
XFS_BLF_CHUNK);
}
static void
xfs_buf_item_format_segment(
struct xfs_buf_log_item *bip,
struct xfs_log_vec *lv,
struct xfs_log_iovec **vecp,
uint offset,
struct xfs_buf_log_format *blfp)
{
struct xfs_buf *bp = bip->bli_buf;
uint base_size;
int first_bit;
int last_bit;
int next_bit;
uint nbits;
/* copy the flags across from the base format item */
blfp->blf_flags = bip->__bli_format.blf_flags;
/*
* Base size is the actual size of the ondisk structure - it reflects
* the actual size of the dirty bitmap rather than the size of the in
* memory structure.
*/
base_size = xfs_buf_log_format_size(blfp);
first_bit = xfs_next_bit(blfp->blf_data_map, blfp->blf_map_size, 0);
if (!(bip->bli_flags & XFS_BLI_STALE) && first_bit == -1) {
/*
* If the map is not be dirty in the transaction, mark
* the size as zero and do not advance the vector pointer.
*/
return;
}
blfp = xlog_copy_iovec(lv, vecp, XLOG_REG_TYPE_BFORMAT, blfp, base_size);
blfp->blf_size = 1;
if (bip->bli_flags & XFS_BLI_STALE) {
/*
* The buffer is stale, so all we need to log
* is the buf log format structure with the
* cancel flag in it.
*/
trace_xfs_buf_item_format_stale(bip);
ASSERT(blfp->blf_flags & XFS_BLF_CANCEL);
return;
}
/*
* Fill in an iovec for each set of contiguous chunks.
*/
last_bit = first_bit;
nbits = 1;
for (;;) {
/*
* This takes the bit number to start looking from and
* returns the next set bit from there. It returns -1
* if there are no more bits set or the start bit is
* beyond the end of the bitmap.
*/
next_bit = xfs_next_bit(blfp->blf_data_map, blfp->blf_map_size,
(uint)last_bit + 1);
/*
* If we run out of bits fill in the last iovec and get out of
* the loop. Else if we start a new set of bits then fill in
* the iovec for the series we were looking at and start
* counting the bits in the new one. Else we're still in the
* same set of bits so just keep counting and scanning.
*/
if (next_bit == -1) {
xfs_buf_item_copy_iovec(lv, vecp, bp, offset,
first_bit, nbits);
blfp->blf_size++;
break;
} else if (next_bit != last_bit + 1 ||
xfs_buf_item_straddle(bp, offset, next_bit, last_bit)) {
xfs_buf_item_copy_iovec(lv, vecp, bp, offset,
first_bit, nbits);
blfp->blf_size++;
first_bit = next_bit;
last_bit = next_bit;
nbits = 1;
} else {
last_bit++;
nbits++;
}
}
}
/*
* This is called to fill in the vector of log iovecs for the
* given log buf item. It fills the first entry with a buf log
* format structure, and the rest point to contiguous chunks
* within the buffer.
*/
STATIC void
xfs_buf_item_format(
struct xfs_log_item *lip,
struct xfs_log_vec *lv)
{
struct xfs_buf_log_item *bip = BUF_ITEM(lip);
struct xfs_buf *bp = bip->bli_buf;
struct xfs_log_iovec *vecp = NULL;
uint offset = 0;
int i;
ASSERT(atomic_read(&bip->bli_refcount) > 0);
ASSERT((bip->bli_flags & XFS_BLI_LOGGED) ||
(bip->bli_flags & XFS_BLI_STALE));
ASSERT((bip->bli_flags & XFS_BLI_STALE) ||
(xfs_blft_from_flags(&bip->__bli_format) > XFS_BLFT_UNKNOWN_BUF
&& xfs_blft_from_flags(&bip->__bli_format) < XFS_BLFT_MAX_BUF));
/*
* If it is an inode buffer, transfer the in-memory state to the
* format flags and clear the in-memory state.
*
* For buffer based inode allocation, we do not transfer
* this state if the inode buffer allocation has not yet been committed
* to the log as setting the XFS_BLI_INODE_BUF flag will prevent
* correct replay of the inode allocation.
*
* For icreate item based inode allocation, the buffers aren't written
* to the journal during allocation, and hence we should always tag the
* buffer as an inode buffer so that the correct unlinked list replay
* occurs during recovery.
*/
if (bip->bli_flags & XFS_BLI_INODE_BUF) {
if (xfs_sb_version_hascrc(&lip->li_mountp->m_sb) ||
!((bip->bli_flags & XFS_BLI_INODE_ALLOC_BUF) &&
xfs_log_item_in_current_chkpt(lip)))
bip->__bli_format.blf_flags |= XFS_BLF_INODE_BUF;
bip->bli_flags &= ~XFS_BLI_INODE_BUF;
}
if ((bip->bli_flags & (XFS_BLI_ORDERED|XFS_BLI_STALE)) ==
XFS_BLI_ORDERED) {
/*
* The buffer has been logged just to order it. It is not being
* included in the transaction commit, so don't format it.
*/
trace_xfs_buf_item_format_ordered(bip);
return;
}
for (i = 0; i < bip->bli_format_count; i++) {
xfs_buf_item_format_segment(bip, lv, &vecp, offset,
&bip->bli_formats[i]);
offset += bp->b_maps[i].bm_len;
}
/*
* Check to make sure everything is consistent.
*/
trace_xfs_buf_item_format(bip);
}
/*
* This is called to pin the buffer associated with the buf log item in memory
* so it cannot be written out.
*
* We also always take a reference to the buffer log item here so that the bli
* is held while the item is pinned in memory. This means that we can
* unconditionally drop the reference count a transaction holds when the
* transaction is completed.
*/
STATIC void
xfs_buf_item_pin(
struct xfs_log_item *lip)
{
struct xfs_buf_log_item *bip = BUF_ITEM(lip);
ASSERT(atomic_read(&bip->bli_refcount) > 0);
ASSERT((bip->bli_flags & XFS_BLI_LOGGED) ||
(bip->bli_flags & XFS_BLI_ORDERED) ||
(bip->bli_flags & XFS_BLI_STALE));
trace_xfs_buf_item_pin(bip);
atomic_inc(&bip->bli_refcount);
atomic_inc(&bip->bli_buf->b_pin_count);
}
/*
* This is called to unpin the buffer associated with the buf log
* item which was previously pinned with a call to xfs_buf_item_pin().
*
* Also drop the reference to the buf item for the current transaction.
* If the XFS_BLI_STALE flag is set and we are the last reference,
* then free up the buf log item and unlock the buffer.
*
* If the remove flag is set we are called from uncommit in the
* forced-shutdown path. If that is true and the reference count on
* the log item is going to drop to zero we need to free the item's
* descriptor in the transaction.
*/
STATIC void
xfs_buf_item_unpin(
struct xfs_log_item *lip,
int remove)
{
struct xfs_buf_log_item *bip = BUF_ITEM(lip);
xfs_buf_t *bp = bip->bli_buf;
struct xfs_ail *ailp = lip->li_ailp;
int stale = bip->bli_flags & XFS_BLI_STALE;
int freed;
ASSERT(bp->b_fspriv == bip);
ASSERT(atomic_read(&bip->bli_refcount) > 0);
trace_xfs_buf_item_unpin(bip);
freed = atomic_dec_and_test(&bip->bli_refcount);
if (atomic_dec_and_test(&bp->b_pin_count))
wake_up_all(&bp->b_waiters);
if (freed && stale) {
ASSERT(bip->bli_flags & XFS_BLI_STALE);
ASSERT(xfs_buf_islocked(bp));
ASSERT(XFS_BUF_ISSTALE(bp));
ASSERT(bip->__bli_format.blf_flags & XFS_BLF_CANCEL);
trace_xfs_buf_item_unpin_stale(bip);
if (remove) {
/*
* If we are in a transaction context, we have to
* remove the log item from the transaction as we are
* about to release our reference to the buffer. If we
* don't, the unlock that occurs later in
* xfs_trans_uncommit() will try to reference the
* buffer which we no longer have a hold on.
*/
if (lip->li_desc)
xfs_trans_del_item(lip);
/*
* Since the transaction no longer refers to the buffer,
* the buffer should no longer refer to the transaction.
*/
bp->b_transp = NULL;
}
/*
* If we get called here because of an IO error, we may
* or may not have the item on the AIL. xfs_trans_ail_delete()
* will take care of that situation.
* xfs_trans_ail_delete() drops the AIL lock.
*/
if (bip->bli_flags & XFS_BLI_STALE_INODE) {
xfs_buf_do_callbacks(bp);
bp->b_fspriv = NULL;
bp->b_iodone = NULL;
} else {
spin_lock(&ailp->xa_lock);
xfs_trans_ail_delete(ailp, lip, SHUTDOWN_LOG_IO_ERROR);
xfs_buf_item_relse(bp);
ASSERT(bp->b_fspriv == NULL);
}
xfs_buf_relse(bp);
} else if (freed && remove) {
/*
* There are currently two references to the buffer - the active
* LRU reference and the buf log item. What we are about to do
* here - simulate a failed IO completion - requires 3
* references.
*
* The LRU reference is removed by the xfs_buf_stale() call. The
* buf item reference is removed by the xfs_buf_iodone()
* callback that is run by xfs_buf_do_callbacks() during ioend
* processing (via the bp->b_iodone callback), and then finally
* the ioend processing will drop the IO reference if the buffer
* is marked XBF_ASYNC.
*
* Hence we need to take an additional reference here so that IO
* completion processing doesn't free the buffer prematurely.
*/
xfs_buf_lock(bp);
xfs_buf_hold(bp);
bp->b_flags |= XBF_ASYNC;
xfs_buf_ioerror(bp, -EIO);
XFS_BUF_UNDONE(bp);
xfs_buf_stale(bp);
xfs_buf_ioend(bp);
}
}
/*
* Buffer IO error rate limiting. Limit it to no more than 10 messages per 30
* seconds so as to not spam logs too much on repeated detection of the same
* buffer being bad..
*/
static DEFINE_RATELIMIT_STATE(xfs_buf_write_fail_rl_state, 30 * HZ, 10);
STATIC uint
xfs_buf_item_push(
struct xfs_log_item *lip,
struct list_head *buffer_list)
{
struct xfs_buf_log_item *bip = BUF_ITEM(lip);
struct xfs_buf *bp = bip->bli_buf;
uint rval = XFS_ITEM_SUCCESS;
if (xfs_buf_ispinned(bp))
return XFS_ITEM_PINNED;
if (!xfs_buf_trylock(bp)) {
/*
* If we have just raced with a buffer being pinned and it has
* been marked stale, we could end up stalling until someone else
* issues a log force to unpin the stale buffer. Check for the
* race condition here so xfsaild recognizes the buffer is pinned
* and queues a log force to move it along.
*/
if (xfs_buf_ispinned(bp))
return XFS_ITEM_PINNED;
return XFS_ITEM_LOCKED;
}
ASSERT(!(bip->bli_flags & XFS_BLI_STALE));
trace_xfs_buf_item_push(bip);
/* has a previous flush failed due to IO errors? */
if ((bp->b_flags & XBF_WRITE_FAIL) &&
___ratelimit(&xfs_buf_write_fail_rl_state, "XFS: Failing async write")) {
xfs_warn(bp->b_target->bt_mount,
"Failing async write on buffer block 0x%llx. Retrying async write.",
(long long)bp->b_bn);
}
if (!xfs_buf_delwri_queue(bp, buffer_list))
rval = XFS_ITEM_FLUSHING;
xfs_buf_unlock(bp);
return rval;
}
/*
* Release the buffer associated with the buf log item. If there is no dirty
* logged data associated with the buffer recorded in the buf log item, then
* free the buf log item and remove the reference to it in the buffer.
*
* This call ignores the recursion count. It is only called when the buffer
* should REALLY be unlocked, regardless of the recursion count.
*
* We unconditionally drop the transaction's reference to the log item. If the
* item was logged, then another reference was taken when it was pinned, so we
* can safely drop the transaction reference now. This also allows us to avoid
* potential races with the unpin code freeing the bli by not referencing the
* bli after we've dropped the reference count.
*
* If the XFS_BLI_HOLD flag is set in the buf log item, then free the log item
* if necessary but do not unlock the buffer. This is for support of
* xfs_trans_bhold(). Make sure the XFS_BLI_HOLD field is cleared if we don't
* free the item.
*/
STATIC void
xfs_buf_item_unlock(
struct xfs_log_item *lip)
{
struct xfs_buf_log_item *bip = BUF_ITEM(lip);
struct xfs_buf *bp = bip->bli_buf;
bool clean;
bool aborted;
int flags;
/* Clear the buffer's association with this transaction. */
bp->b_transp = NULL;
/*
* If this is a transaction abort, don't return early. Instead, allow
* the brelse to happen. Normally it would be done for stale
* (cancelled) buffers at unpin time, but we'll never go through the
* pin/unpin cycle if we abort inside commit.
*/
aborted = (lip->li_flags & XFS_LI_ABORTED) ? true : false;
/*
* Before possibly freeing the buf item, copy the per-transaction state
* so we can reference it safely later after clearing it from the
* buffer log item.
*/
flags = bip->bli_flags;
bip->bli_flags &= ~(XFS_BLI_LOGGED | XFS_BLI_HOLD | XFS_BLI_ORDERED);
/*
* If the buf item is marked stale, then don't do anything. We'll
* unlock the buffer and free the buf item when the buffer is unpinned
* for the last time.
*/
if (flags & XFS_BLI_STALE) {
trace_xfs_buf_item_unlock_stale(bip);
ASSERT(bip->__bli_format.blf_flags & XFS_BLF_CANCEL);
if (!aborted) {
atomic_dec(&bip->bli_refcount);
return;
}
}
trace_xfs_buf_item_unlock(bip);
/*
* If the buf item isn't tracking any data, free it, otherwise drop the
* reference we hold to it. If we are aborting the transaction, this may
* be the only reference to the buf item, so we free it anyway
* regardless of whether it is dirty or not. A dirty abort implies a
* shutdown, anyway.
*
* Ordered buffers are dirty but may have no recorded changes, so ensure
* we only release clean items here.
*/
clean = (flags & XFS_BLI_DIRTY) ? false : true;
if (clean) {
int i;
for (i = 0; i < bip->bli_format_count; i++) {
if (!xfs_bitmap_empty(bip->bli_formats[i].blf_data_map,
bip->bli_formats[i].blf_map_size)) {
clean = false;
break;
}
}
}
/*
* Clean buffers, by definition, cannot be in the AIL. However, aborted
* buffers may be dirty and hence in the AIL. Therefore if we are
* aborting a buffer and we've just taken the last refernce away, we
* have to check if it is in the AIL before freeing it. We need to free
* it in this case, because an aborted transaction has already shut the
* filesystem down and this is the last chance we will have to do so.
*/
if (atomic_dec_and_test(&bip->bli_refcount)) {
if (clean)
xfs_buf_item_relse(bp);
else if (aborted) {
ASSERT(XFS_FORCED_SHUTDOWN(lip->li_mountp));
xfs_trans_ail_remove(lip, SHUTDOWN_LOG_IO_ERROR);
xfs_buf_item_relse(bp);
}
}
if (!(flags & XFS_BLI_HOLD))
xfs_buf_relse(bp);
}
/*
* This is called to find out where the oldest active copy of the
* buf log item in the on disk log resides now that the last log
* write of it completed at the given lsn.
* We always re-log all the dirty data in a buffer, so usually the
* latest copy in the on disk log is the only one that matters. For
* those cases we simply return the given lsn.
*
* The one exception to this is for buffers full of newly allocated
* inodes. These buffers are only relogged with the XFS_BLI_INODE_BUF
* flag set, indicating that only the di_next_unlinked fields from the
* inodes in the buffers will be replayed during recovery. If the
* original newly allocated inode images have not yet been flushed
* when the buffer is so relogged, then we need to make sure that we
* keep the old images in the 'active' portion of the log. We do this
* by returning the original lsn of that transaction here rather than
* the current one.
*/
STATIC xfs_lsn_t
xfs_buf_item_committed(
struct xfs_log_item *lip,
xfs_lsn_t lsn)
{
struct xfs_buf_log_item *bip = BUF_ITEM(lip);
trace_xfs_buf_item_committed(bip);
if ((bip->bli_flags & XFS_BLI_INODE_ALLOC_BUF) && lip->li_lsn != 0)
return lip->li_lsn;
return lsn;
}
STATIC void
xfs_buf_item_committing(
struct xfs_log_item *lip,
xfs_lsn_t commit_lsn)
{
}
/*
* This is the ops vector shared by all buf log items.
*/
static const struct xfs_item_ops xfs_buf_item_ops = {
.iop_size = xfs_buf_item_size,
.iop_format = xfs_buf_item_format,
.iop_pin = xfs_buf_item_pin,
.iop_unpin = xfs_buf_item_unpin,
.iop_unlock = xfs_buf_item_unlock,
.iop_committed = xfs_buf_item_committed,
.iop_push = xfs_buf_item_push,
.iop_committing = xfs_buf_item_committing
};
STATIC int
xfs_buf_item_get_format(
struct xfs_buf_log_item *bip,
int count)
{
ASSERT(bip->bli_formats == NULL);
bip->bli_format_count = count;
if (count == 1) {
bip->bli_formats = &bip->__bli_format;
return 0;
}
bip->bli_formats = kmem_zalloc(count * sizeof(struct xfs_buf_log_format),
KM_SLEEP);
if (!bip->bli_formats)
return -ENOMEM;
return 0;
}
STATIC void
xfs_buf_item_free_format(
struct xfs_buf_log_item *bip)
{
if (bip->bli_formats != &bip->__bli_format) {
kmem_free(bip->bli_formats);
bip->bli_formats = NULL;
}
}
/*
* Allocate a new buf log item to go with the given buffer.
* Set the buffer's b_fsprivate field to point to the new
* buf log item. If there are other item's attached to the
* buffer (see xfs_buf_attach_iodone() below), then put the
* buf log item at the front.
*/
int
xfs_buf_item_init(
struct xfs_buf *bp,
struct xfs_mount *mp)
{
struct xfs_log_item *lip = bp->b_fspriv;
struct xfs_buf_log_item *bip;
int chunks;
int map_size;
int error;
int i;
/*
* Check to see if there is already a buf log item for
* this buffer. If there is, it is guaranteed to be
* the first. If we do already have one, there is
* nothing to do here so return.
*/
ASSERT(bp->b_target->bt_mount == mp);
if (lip != NULL && lip->li_type == XFS_LI_BUF)
return 0;
bip = kmem_zone_zalloc(xfs_buf_item_zone, KM_SLEEP);
xfs_log_item_init(mp, &bip->bli_item, XFS_LI_BUF, &xfs_buf_item_ops);
bip->bli_buf = bp;
/*
* chunks is the number of XFS_BLF_CHUNK size pieces the buffer
* can be divided into. Make sure not to truncate any pieces.
* map_size is the size of the bitmap needed to describe the
* chunks of the buffer.
*
* Discontiguous buffer support follows the layout of the underlying
* buffer. This makes the implementation as simple as possible.
*/
error = xfs_buf_item_get_format(bip, bp->b_map_count);
ASSERT(error == 0);
if (error) { /* to stop gcc throwing set-but-unused warnings */
kmem_zone_free(xfs_buf_item_zone, bip);
return error;
}
for (i = 0; i < bip->bli_format_count; i++) {
chunks = DIV_ROUND_UP(BBTOB(bp->b_maps[i].bm_len),
XFS_BLF_CHUNK);
map_size = DIV_ROUND_UP(chunks, NBWORD);
bip->bli_formats[i].blf_type = XFS_LI_BUF;
bip->bli_formats[i].blf_blkno = bp->b_maps[i].bm_bn;
bip->bli_formats[i].blf_len = bp->b_maps[i].bm_len;
bip->bli_formats[i].blf_map_size = map_size;
}
/*
* Put the buf item into the list of items attached to the
* buffer at the front.
*/
if (bp->b_fspriv)
bip->bli_item.li_bio_list = bp->b_fspriv;
bp->b_fspriv = bip;
xfs_buf_hold(bp);
return 0;
}
/*
* Mark bytes first through last inclusive as dirty in the buf
* item's bitmap.
*/
static void
xfs_buf_item_log_segment(
uint first,
uint last,
uint *map)
{
uint first_bit;
uint last_bit;
uint bits_to_set;
uint bits_set;
uint word_num;
uint *wordp;
uint bit;
uint end_bit;
uint mask;
/*
* Convert byte offsets to bit numbers.
*/
first_bit = first >> XFS_BLF_SHIFT;
last_bit = last >> XFS_BLF_SHIFT;
/*
* Calculate the total number of bits to be set.
*/
bits_to_set = last_bit - first_bit + 1;
/*
* Get a pointer to the first word in the bitmap
* to set a bit in.
*/
word_num = first_bit >> BIT_TO_WORD_SHIFT;
wordp = &map[word_num];
/*
* Calculate the starting bit in the first word.
*/
bit = first_bit & (uint)(NBWORD - 1);
/*
* First set any bits in the first word of our range.
* If it starts at bit 0 of the word, it will be
* set below rather than here. That is what the variable
* bit tells us. The variable bits_set tracks the number
* of bits that have been set so far. End_bit is the number
* of the last bit to be set in this word plus one.
*/
if (bit) {
end_bit = MIN(bit + bits_to_set, (uint)NBWORD);
mask = ((1 << (end_bit - bit)) - 1) << bit;
*wordp |= mask;
wordp++;
bits_set = end_bit - bit;
} else {
bits_set = 0;
}
/*
* Now set bits a whole word at a time that are between
* first_bit and last_bit.
*/
while ((bits_to_set - bits_set) >= NBWORD) {
*wordp |= 0xffffffff;
bits_set += NBWORD;
wordp++;
}
/*
* Finally, set any bits left to be set in one last partial word.
*/
end_bit = bits_to_set - bits_set;
if (end_bit) {
mask = (1 << end_bit) - 1;
*wordp |= mask;
}
}
/*
* Mark bytes first through last inclusive as dirty in the buf
* item's bitmap.
*/
void
xfs_buf_item_log(
xfs_buf_log_item_t *bip,
uint first,
uint last)
{
int i;
uint start;
uint end;
struct xfs_buf *bp = bip->bli_buf;
/*
* walk each buffer segment and mark them dirty appropriately.
*/
start = 0;
for (i = 0; i < bip->bli_format_count; i++) {
if (start > last)
break;
end = start + BBTOB(bp->b_maps[i].bm_len);
if (first > end) {
start += BBTOB(bp->b_maps[i].bm_len);
continue;
}
if (first < start)
first = start;
if (end > last)
end = last;
xfs_buf_item_log_segment(first, end,
&bip->bli_formats[i].blf_data_map[0]);
start += bp->b_maps[i].bm_len;
}
}
/*
* Return 1 if the buffer has been logged or ordered in a transaction (at any
* point, not just the current transaction) and 0 if not.
*/
uint
xfs_buf_item_dirty(
xfs_buf_log_item_t *bip)
{
return (bip->bli_flags & XFS_BLI_DIRTY);
}
STATIC void
xfs_buf_item_free(
xfs_buf_log_item_t *bip)
{
xfs_buf_item_free_format(bip);
kmem_zone_free(xfs_buf_item_zone, bip);
}
/*
* This is called when the buf log item is no longer needed. It should
* free the buf log item associated with the given buffer and clear
* the buffer's pointer to the buf log item. If there are no more
* items in the list, clear the b_iodone field of the buffer (see
* xfs_buf_attach_iodone() below).
*/
void
xfs_buf_item_relse(
xfs_buf_t *bp)
{
xfs_buf_log_item_t *bip = bp->b_fspriv;
trace_xfs_buf_item_relse(bp, _RET_IP_);
ASSERT(!(bip->bli_item.li_flags & XFS_LI_IN_AIL));
bp->b_fspriv = bip->bli_item.li_bio_list;
if (bp->b_fspriv == NULL)
bp->b_iodone = NULL;
xfs_buf_rele(bp);
xfs_buf_item_free(bip);
}
/*
* Add the given log item with its callback to the list of callbacks
* to be called when the buffer's I/O completes. If it is not set
* already, set the buffer's b_iodone() routine to be
* xfs_buf_iodone_callbacks() and link the log item into the list of
* items rooted at b_fsprivate. Items are always added as the second
* entry in the list if there is a first, because the buf item code
* assumes that the buf log item is first.
*/
void
xfs_buf_attach_iodone(
xfs_buf_t *bp,
void (*cb)(xfs_buf_t *, xfs_log_item_t *),
xfs_log_item_t *lip)
{
xfs_log_item_t *head_lip;
ASSERT(xfs_buf_islocked(bp));
lip->li_cb = cb;
head_lip = bp->b_fspriv;
if (head_lip) {
lip->li_bio_list = head_lip->li_bio_list;
head_lip->li_bio_list = lip;
} else {
bp->b_fspriv = lip;
}
ASSERT(bp->b_iodone == NULL ||
bp->b_iodone == xfs_buf_iodone_callbacks);
bp->b_iodone = xfs_buf_iodone_callbacks;
}
/*
* We can have many callbacks on a buffer. Running the callbacks individually
* can cause a lot of contention on the AIL lock, so we allow for a single
* callback to be able to scan the remaining lip->li_bio_list for other items
* of the same type and callback to be processed in the first call.
*
* As a result, the loop walking the callback list below will also modify the
* list. it removes the first item from the list and then runs the callback.
* The loop then restarts from the new head of the list. This allows the
* callback to scan and modify the list attached to the buffer and we don't
* have to care about maintaining a next item pointer.
*/
STATIC void
xfs_buf_do_callbacks(
struct xfs_buf *bp)
{
struct xfs_log_item *lip;
while ((lip = bp->b_fspriv) != NULL) {
bp->b_fspriv = lip->li_bio_list;
ASSERT(lip->li_cb != NULL);
/*
* Clear the next pointer so we don't have any
* confusion if the item is added to another buf.
* Don't touch the log item after calling its
* callback, because it could have freed itself.
*/
lip->li_bio_list = NULL;
lip->li_cb(bp, lip);
}
}
/*
* This is the iodone() function for buffers which have had callbacks
* attached to them by xfs_buf_attach_iodone(). It should remove each
* log item from the buffer's list and call the callback of each in turn.
* When done, the buffer's fsprivate field is set to NULL and the buffer
* is unlocked with a call to iodone().
*/
void
xfs_buf_iodone_callbacks(
struct xfs_buf *bp)
{
struct xfs_log_item *lip = bp->b_fspriv;
struct xfs_mount *mp = lip->li_mountp;
static ulong lasttime;
static xfs_buftarg_t *lasttarg;
if (likely(!bp->b_error))
goto do_callbacks;
/*
* If we've already decided to shutdown the filesystem because of
* I/O errors, there's no point in giving this a retry.
*/
if (XFS_FORCED_SHUTDOWN(mp)) {
xfs_buf_stale(bp);
XFS_BUF_DONE(bp);
trace_xfs_buf_item_iodone(bp, _RET_IP_);
goto do_callbacks;
}
if (bp->b_target != lasttarg ||
time_after(jiffies, (lasttime + 5*HZ))) {
lasttime = jiffies;
xfs_buf_ioerror_alert(bp, __func__);
}
lasttarg = bp->b_target;
/*
* If the write was asynchronous then no one will be looking for the
* error. Clear the error state and write the buffer out again.
*
* XXX: This helps against transient write errors, but we need to find
* a way to shut the filesystem down if the writes keep failing.
*
* In practice we'll shut the filesystem down soon as non-transient
* errors tend to affect the whole device and a failing log write
* will make us give up. But we really ought to do better here.
*/
if (XFS_BUF_ISASYNC(bp)) {
ASSERT(bp->b_iodone != NULL);
trace_xfs_buf_item_iodone_async(bp, _RET_IP_);
xfs_buf_ioerror(bp, 0); /* errno of 0 unsets the flag */
if (!(bp->b_flags & (XBF_STALE|XBF_WRITE_FAIL))) {
bp->b_flags |= XBF_WRITE | XBF_ASYNC |
XBF_DONE | XBF_WRITE_FAIL;
xfs_buf_submit(bp);
} else {
xfs_buf_relse(bp);
}
return;
}
/*
* If the write of the buffer was synchronous, we want to make
* sure to return the error to the caller of xfs_bwrite().
*/
xfs_buf_stale(bp);
XFS_BUF_DONE(bp);
trace_xfs_buf_error_relse(bp, _RET_IP_);
do_callbacks:
xfs_buf_do_callbacks(bp);
bp->b_fspriv = NULL;
bp->b_iodone = NULL;
xfs_buf_ioend(bp);
}
/*
* This is the iodone() function for buffers which have been
* logged. It is called when they are eventually flushed out.
* It should remove the buf item from the AIL, and free the buf item.
* It is called by xfs_buf_iodone_callbacks() above which will take
* care of cleaning up the buffer itself.
*/
void
xfs_buf_iodone(
struct xfs_buf *bp,
struct xfs_log_item *lip)
{
struct xfs_ail *ailp = lip->li_ailp;
ASSERT(BUF_ITEM(lip)->bli_buf == bp);
xfs_buf_rele(bp);
/*
* If we are forcibly shutting down, this may well be
* off the AIL already. That's because we simulate the
* log-committed callbacks to unpin these buffers. Or we may never
* have put this item on AIL because of the transaction was
* aborted forcibly. xfs_trans_ail_delete() takes care of these.
*
* Either way, AIL is useless if we're forcing a shutdown.
*/
spin_lock(&ailp->xa_lock);
xfs_trans_ail_delete(ailp, lip, SHUTDOWN_CORRUPT_INCORE);
xfs_buf_item_free(BUF_ITEM(lip));
}