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![Brian Foster](/assets/img/avatar_default.png)
xfs_buftarg_drain() is called from xfs_log_quiesce() to ensure the buffer cache is reclaimed during unmount. xfs_log_quiesce() is also called from xfs_quiesce_attr(), however, which means that cache state is completely drained for filesystem freeze and read-only remount. While technically harmless, this is unnecessarily heavyweight. Both freeze and read-only mounts allow reads and thus allow population of the buffer cache. Therefore, the transitional sequence in either case really only needs to quiesce outstanding writes to return the filesystem in a generally read-only state. Additionally, some users have reported that attempts to freeze a filesystem concurrent with a read-heavy workload causes the freeze process to stall for a significant amount of time. This occurs because, as mentioned above, the read workload repopulates the buffer LRU while the freeze task attempts to drain it. To improve this situation, replace the drain in xfs_log_quiesce() with a buffer I/O quiesce and lift the drain into the unmount path. This removes buffer LRU reclaim from freeze and read-only [re]mount, but ensures the LRU is still drained before the filesystem unmounts. Signed-off-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Darrick J. Wong <djwong@kernel.org> Signed-off-by: Darrick J. Wong <djwong@kernel.org>
367 lines
12 KiB
C
367 lines
12 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (c) 2000-2005 Silicon Graphics, Inc.
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* All Rights Reserved.
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*/
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#ifndef __XFS_BUF_H__
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#define __XFS_BUF_H__
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#include <linux/list.h>
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#include <linux/types.h>
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#include <linux/spinlock.h>
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#include <linux/mm.h>
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#include <linux/fs.h>
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#include <linux/dax.h>
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#include <linux/uio.h>
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#include <linux/list_lru.h>
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/*
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* Base types
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*/
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struct xfs_buf;
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#define XFS_BUF_DADDR_NULL ((xfs_daddr_t) (-1LL))
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#define XBF_READ (1 << 0) /* buffer intended for reading from device */
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#define XBF_WRITE (1 << 1) /* buffer intended for writing to device */
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#define XBF_READ_AHEAD (1 << 2) /* asynchronous read-ahead */
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#define XBF_NO_IOACCT (1 << 3) /* bypass I/O accounting (non-LRU bufs) */
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#define XBF_ASYNC (1 << 4) /* initiator will not wait for completion */
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#define XBF_DONE (1 << 5) /* all pages in the buffer uptodate */
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#define XBF_STALE (1 << 6) /* buffer has been staled, do not find it */
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#define XBF_WRITE_FAIL (1 << 7) /* async writes have failed on this buffer */
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/* buffer type flags for write callbacks */
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#define _XBF_INODES (1 << 16)/* inode buffer */
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#define _XBF_DQUOTS (1 << 17)/* dquot buffer */
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#define _XBF_LOGRECOVERY (1 << 18)/* log recovery buffer */
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/* flags used only internally */
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#define _XBF_PAGES (1 << 20)/* backed by refcounted pages */
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#define _XBF_KMEM (1 << 21)/* backed by heap memory */
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#define _XBF_DELWRI_Q (1 << 22)/* buffer on a delwri queue */
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/* flags used only as arguments to access routines */
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#define XBF_TRYLOCK (1 << 30)/* lock requested, but do not wait */
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#define XBF_UNMAPPED (1 << 31)/* do not map the buffer */
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typedef unsigned int xfs_buf_flags_t;
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#define XFS_BUF_FLAGS \
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{ XBF_READ, "READ" }, \
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{ XBF_WRITE, "WRITE" }, \
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{ XBF_READ_AHEAD, "READ_AHEAD" }, \
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{ XBF_NO_IOACCT, "NO_IOACCT" }, \
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{ XBF_ASYNC, "ASYNC" }, \
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{ XBF_DONE, "DONE" }, \
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{ XBF_STALE, "STALE" }, \
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{ XBF_WRITE_FAIL, "WRITE_FAIL" }, \
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{ _XBF_INODES, "INODES" }, \
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{ _XBF_DQUOTS, "DQUOTS" }, \
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{ _XBF_LOGRECOVERY, "LOG_RECOVERY" }, \
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{ _XBF_PAGES, "PAGES" }, \
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{ _XBF_KMEM, "KMEM" }, \
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{ _XBF_DELWRI_Q, "DELWRI_Q" }, \
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/* The following interface flags should never be set */ \
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{ XBF_TRYLOCK, "TRYLOCK" }, \
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{ XBF_UNMAPPED, "UNMAPPED" }
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/*
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* Internal state flags.
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*/
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#define XFS_BSTATE_DISPOSE (1 << 0) /* buffer being discarded */
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#define XFS_BSTATE_IN_FLIGHT (1 << 1) /* I/O in flight */
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/*
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* The xfs_buftarg contains 2 notions of "sector size" -
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*
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* 1) The metadata sector size, which is the minimum unit and
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* alignment of IO which will be performed by metadata operations.
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* 2) The device logical sector size
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*
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* The first is specified at mkfs time, and is stored on-disk in the
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* superblock's sb_sectsize.
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*
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* The latter is derived from the underlying device, and controls direct IO
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* alignment constraints.
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*/
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typedef struct xfs_buftarg {
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dev_t bt_dev;
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struct block_device *bt_bdev;
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struct dax_device *bt_daxdev;
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struct xfs_mount *bt_mount;
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unsigned int bt_meta_sectorsize;
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size_t bt_meta_sectormask;
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size_t bt_logical_sectorsize;
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size_t bt_logical_sectormask;
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/* LRU control structures */
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struct shrinker bt_shrinker;
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struct list_lru bt_lru;
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struct percpu_counter bt_io_count;
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struct ratelimit_state bt_ioerror_rl;
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} xfs_buftarg_t;
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#define XB_PAGES 2
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struct xfs_buf_map {
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xfs_daddr_t bm_bn; /* block number for I/O */
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int bm_len; /* size of I/O */
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};
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#define DEFINE_SINGLE_BUF_MAP(map, blkno, numblk) \
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struct xfs_buf_map (map) = { .bm_bn = (blkno), .bm_len = (numblk) };
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struct xfs_buf_ops {
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char *name;
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union {
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__be32 magic[2]; /* v4 and v5 on disk magic values */
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__be16 magic16[2]; /* v4 and v5 on disk magic values */
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};
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void (*verify_read)(struct xfs_buf *);
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void (*verify_write)(struct xfs_buf *);
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xfs_failaddr_t (*verify_struct)(struct xfs_buf *bp);
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};
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struct xfs_buf {
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/*
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* first cacheline holds all the fields needed for an uncontended cache
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* hit to be fully processed. The semaphore straddles the cacheline
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* boundary, but the counter and lock sits on the first cacheline,
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* which is the only bit that is touched if we hit the semaphore
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* fast-path on locking.
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*/
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struct rhash_head b_rhash_head; /* pag buffer hash node */
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xfs_daddr_t b_bn; /* block number of buffer */
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int b_length; /* size of buffer in BBs */
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atomic_t b_hold; /* reference count */
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atomic_t b_lru_ref; /* lru reclaim ref count */
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xfs_buf_flags_t b_flags; /* status flags */
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struct semaphore b_sema; /* semaphore for lockables */
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/*
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* concurrent access to b_lru and b_lru_flags are protected by
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* bt_lru_lock and not by b_sema
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*/
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struct list_head b_lru; /* lru list */
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spinlock_t b_lock; /* internal state lock */
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unsigned int b_state; /* internal state flags */
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int b_io_error; /* internal IO error state */
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wait_queue_head_t b_waiters; /* unpin waiters */
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struct list_head b_list;
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struct xfs_perag *b_pag; /* contains rbtree root */
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struct xfs_mount *b_mount;
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struct xfs_buftarg *b_target; /* buffer target (device) */
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void *b_addr; /* virtual address of buffer */
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struct work_struct b_ioend_work;
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struct completion b_iowait; /* queue for I/O waiters */
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struct xfs_buf_log_item *b_log_item;
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struct list_head b_li_list; /* Log items list head */
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struct xfs_trans *b_transp;
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struct page **b_pages; /* array of page pointers */
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struct page *b_page_array[XB_PAGES]; /* inline pages */
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struct xfs_buf_map *b_maps; /* compound buffer map */
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struct xfs_buf_map __b_map; /* inline compound buffer map */
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int b_map_count;
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atomic_t b_pin_count; /* pin count */
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atomic_t b_io_remaining; /* #outstanding I/O requests */
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unsigned int b_page_count; /* size of page array */
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unsigned int b_offset; /* page offset in first page */
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int b_error; /* error code on I/O */
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/*
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* async write failure retry count. Initialised to zero on the first
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* failure, then when it exceeds the maximum configured without a
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* success the write is considered to be failed permanently and the
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* iodone handler will take appropriate action.
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*
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* For retry timeouts, we record the jiffie of the first failure. This
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* means that we can change the retry timeout for buffers already under
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* I/O and thus avoid getting stuck in a retry loop with a long timeout.
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*
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* last_error is used to ensure that we are getting repeated errors, not
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* different errors. e.g. a block device might change ENOSPC to EIO when
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* a failure timeout occurs, so we want to re-initialise the error
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* retry behaviour appropriately when that happens.
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*/
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int b_retries;
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unsigned long b_first_retry_time; /* in jiffies */
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int b_last_error;
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const struct xfs_buf_ops *b_ops;
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};
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/* Finding and Reading Buffers */
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struct xfs_buf *xfs_buf_incore(struct xfs_buftarg *target,
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xfs_daddr_t blkno, size_t numblks,
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xfs_buf_flags_t flags);
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int xfs_buf_get_map(struct xfs_buftarg *target, struct xfs_buf_map *map,
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int nmaps, xfs_buf_flags_t flags, struct xfs_buf **bpp);
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int xfs_buf_read_map(struct xfs_buftarg *target, struct xfs_buf_map *map,
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int nmaps, xfs_buf_flags_t flags, struct xfs_buf **bpp,
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const struct xfs_buf_ops *ops, xfs_failaddr_t fa);
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void xfs_buf_readahead_map(struct xfs_buftarg *target,
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struct xfs_buf_map *map, int nmaps,
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const struct xfs_buf_ops *ops);
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static inline int
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xfs_buf_get(
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struct xfs_buftarg *target,
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xfs_daddr_t blkno,
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size_t numblks,
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struct xfs_buf **bpp)
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{
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DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
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return xfs_buf_get_map(target, &map, 1, 0, bpp);
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}
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static inline int
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xfs_buf_read(
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struct xfs_buftarg *target,
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xfs_daddr_t blkno,
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size_t numblks,
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xfs_buf_flags_t flags,
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struct xfs_buf **bpp,
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const struct xfs_buf_ops *ops)
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{
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DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
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return xfs_buf_read_map(target, &map, 1, flags, bpp, ops,
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__builtin_return_address(0));
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}
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static inline void
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xfs_buf_readahead(
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struct xfs_buftarg *target,
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xfs_daddr_t blkno,
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size_t numblks,
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const struct xfs_buf_ops *ops)
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{
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DEFINE_SINGLE_BUF_MAP(map, blkno, numblks);
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return xfs_buf_readahead_map(target, &map, 1, ops);
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}
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int xfs_buf_get_uncached(struct xfs_buftarg *target, size_t numblks, int flags,
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struct xfs_buf **bpp);
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int xfs_buf_read_uncached(struct xfs_buftarg *target, xfs_daddr_t daddr,
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size_t numblks, int flags, struct xfs_buf **bpp,
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const struct xfs_buf_ops *ops);
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int _xfs_buf_read(struct xfs_buf *bp, xfs_buf_flags_t flags);
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void xfs_buf_hold(struct xfs_buf *bp);
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/* Releasing Buffers */
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extern void xfs_buf_rele(struct xfs_buf *);
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/* Locking and Unlocking Buffers */
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extern int xfs_buf_trylock(struct xfs_buf *);
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extern void xfs_buf_lock(struct xfs_buf *);
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extern void xfs_buf_unlock(struct xfs_buf *);
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#define xfs_buf_islocked(bp) \
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((bp)->b_sema.count <= 0)
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static inline void xfs_buf_relse(struct xfs_buf *bp)
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{
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xfs_buf_unlock(bp);
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xfs_buf_rele(bp);
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}
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/* Buffer Read and Write Routines */
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extern int xfs_bwrite(struct xfs_buf *bp);
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extern void __xfs_buf_ioerror(struct xfs_buf *bp, int error,
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xfs_failaddr_t failaddr);
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#define xfs_buf_ioerror(bp, err) __xfs_buf_ioerror((bp), (err), __this_address)
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extern void xfs_buf_ioerror_alert(struct xfs_buf *bp, xfs_failaddr_t fa);
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void xfs_buf_ioend_fail(struct xfs_buf *);
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void xfs_buf_zero(struct xfs_buf *bp, size_t boff, size_t bsize);
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void __xfs_buf_mark_corrupt(struct xfs_buf *bp, xfs_failaddr_t fa);
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#define xfs_buf_mark_corrupt(bp) __xfs_buf_mark_corrupt((bp), __this_address)
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/* Buffer Utility Routines */
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extern void *xfs_buf_offset(struct xfs_buf *, size_t);
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extern void xfs_buf_stale(struct xfs_buf *bp);
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/* Delayed Write Buffer Routines */
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extern void xfs_buf_delwri_cancel(struct list_head *);
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extern bool xfs_buf_delwri_queue(struct xfs_buf *, struct list_head *);
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extern int xfs_buf_delwri_submit(struct list_head *);
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extern int xfs_buf_delwri_submit_nowait(struct list_head *);
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extern int xfs_buf_delwri_pushbuf(struct xfs_buf *, struct list_head *);
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/* Buffer Daemon Setup Routines */
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extern int xfs_buf_init(void);
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extern void xfs_buf_terminate(void);
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/*
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* These macros use the IO block map rather than b_bn. b_bn is now really
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* just for the buffer cache index for cached buffers. As IO does not use b_bn
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* anymore, uncached buffers do not use b_bn at all and hence must modify the IO
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* map directly. Uncached buffers are not allowed to be discontiguous, so this
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* is safe to do.
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*
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* In future, uncached buffers will pass the block number directly to the io
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* request function and hence these macros will go away at that point.
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*/
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#define XFS_BUF_ADDR(bp) ((bp)->b_maps[0].bm_bn)
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#define XFS_BUF_SET_ADDR(bp, bno) ((bp)->b_maps[0].bm_bn = (xfs_daddr_t)(bno))
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void xfs_buf_set_ref(struct xfs_buf *bp, int lru_ref);
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/*
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* If the buffer is already on the LRU, do nothing. Otherwise set the buffer
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* up with a reference count of 0 so it will be tossed from the cache when
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* released.
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*/
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static inline void xfs_buf_oneshot(struct xfs_buf *bp)
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{
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if (!list_empty(&bp->b_lru) || atomic_read(&bp->b_lru_ref) > 1)
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return;
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atomic_set(&bp->b_lru_ref, 0);
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}
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static inline int xfs_buf_ispinned(struct xfs_buf *bp)
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{
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return atomic_read(&bp->b_pin_count);
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}
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static inline int
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xfs_buf_verify_cksum(struct xfs_buf *bp, unsigned long cksum_offset)
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{
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return xfs_verify_cksum(bp->b_addr, BBTOB(bp->b_length),
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cksum_offset);
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}
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static inline void
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xfs_buf_update_cksum(struct xfs_buf *bp, unsigned long cksum_offset)
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{
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xfs_update_cksum(bp->b_addr, BBTOB(bp->b_length),
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cksum_offset);
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}
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/*
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* Handling of buftargs.
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*/
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extern struct xfs_buftarg *xfs_alloc_buftarg(struct xfs_mount *,
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struct block_device *, struct dax_device *);
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extern void xfs_free_buftarg(struct xfs_buftarg *);
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extern void xfs_buftarg_wait(struct xfs_buftarg *);
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extern void xfs_buftarg_drain(struct xfs_buftarg *);
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extern int xfs_setsize_buftarg(struct xfs_buftarg *, unsigned int);
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#define xfs_getsize_buftarg(buftarg) block_size((buftarg)->bt_bdev)
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#define xfs_readonly_buftarg(buftarg) bdev_read_only((buftarg)->bt_bdev)
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static inline int
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xfs_buftarg_dma_alignment(struct xfs_buftarg *bt)
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{
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return queue_dma_alignment(bt->bt_bdev->bd_disk->queue);
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}
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int xfs_buf_reverify(struct xfs_buf *bp, const struct xfs_buf_ops *ops);
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bool xfs_verify_magic(struct xfs_buf *bp, __be32 dmagic);
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bool xfs_verify_magic16(struct xfs_buf *bp, __be16 dmagic);
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#endif /* __XFS_BUF_H__ */
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