// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2010, 2023 Red Hat, Inc.
* All Rights Reserved.
*/
#include "xfs.h"
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_log_format.h"
#include "xfs_trans_resv.h"
#include "xfs_trans.h"
#include "xfs_mount.h"
#include "xfs_btree.h"
#include "xfs_alloc_btree.h"
#include "xfs_alloc.h"
#include "xfs_discard.h"
#include "xfs_error.h"
#include "xfs_extent_busy.h"
#include "xfs_trace.h"
#include "xfs_log.h"
#include "xfs_ag.h"
#include "xfs_health.h"
#include "xfs_rtbitmap.h"
/*
* Notes on an efficient, low latency fstrim algorithm
*
* We need to walk the filesystem free space and issue discards on the free
* space that meet the search criteria (size and location). We cannot issue
* discards on extents that might be in use, or are so recently in use they are
* still marked as busy. To serialise against extent state changes whilst we are
* gathering extents to trim, we must hold the AGF lock to lock out other
* allocations and extent free operations that might change extent state.
*
* However, we cannot just hold the AGF for the entire AG free space walk whilst
* we issue discards on each free space that is found. Storage devices can have
* extremely slow discard implementations (e.g. ceph RBD) and so walking a
* couple of million free extents and issuing synchronous discards on each
* extent can take a *long* time. Whilst we are doing this walk, nothing else
* can access the AGF, and we can stall transactions and hence the log whilst
* modifications wait for the AGF lock to be released. This can lead hung tasks
* kicking the hung task timer and rebooting the system. This is bad.
*
* Hence we need to take a leaf from the bulkstat playbook. It takes the AGI
* lock, gathers a range of inode cluster buffers that are allocated, drops the
* AGI lock and then reads all the inode cluster buffers and processes them. It
* loops doing this, using a cursor to keep track of where it is up to in the AG
* for each iteration to restart the INOBT lookup from.
*
* We can't do this exactly with free space - once we drop the AGF lock, the
* state of the free extent is out of our control and we cannot run a discard
* safely on it in this situation. Unless, of course, we've marked the free
* extent as busy and undergoing a discard operation whilst we held the AGF
* locked.
*
* This is exactly how online discard works - free extents are marked busy when
* they are freed, and once the extent free has been committed to the journal,
* the busy extent record is marked as "undergoing discard" and the discard is
* then issued on the free extent. Once the discard completes, the busy extent
* record is removed and the extent is able to be allocated again.
*
* In the context of fstrim, if we find a free extent we need to discard, we
* don't have to discard it immediately. All we need to do it record that free
* extent as being busy and under discard, and all the allocation routines will
* now avoid trying to allocate it. Hence if we mark the extent as busy under
* the AGF lock, we can safely discard it without holding the AGF lock because
* nothing will attempt to allocate that free space until the discard completes.
*
* This also allows us to issue discards asynchronously like we do with online
* discard, and so for fast devices fstrim will run much faster as we can have
* multiple discard operations in flight at once, as well as pipeline the free
* extent search so that it overlaps in flight discard IO.
*/
struct workqueue_struct *xfs_discard_wq;
static void
xfs_discard_endio_work(
struct work_struct *work)
{
struct xfs_busy_extents *extents =
container_of(work, struct xfs_busy_extents, endio_work);
xfs_extent_busy_clear(extents->mount, &extents->extent_list, false);
kfree(extents->owner);
}
/*
* Queue up the actual completion to a thread to avoid IRQ-safe locking for
* pagb_lock.
*/
static void
xfs_discard_endio(
struct bio *bio)
{
struct xfs_busy_extents *extents = bio->bi_private;
INIT_WORK(&extents->endio_work, xfs_discard_endio_work);
queue_work(xfs_discard_wq, &extents->endio_work);
bio_put(bio);
}
/*
* Walk the discard list and issue discards on all the busy extents in the
* list. We plug and chain the bios so that we only need a single completion
* call to clear all the busy extents once the discards are complete.
*/
int
xfs_discard_extents(
struct xfs_mount *mp,
struct xfs_busy_extents *extents)
{
struct xfs_extent_busy *busyp;
struct bio *bio = NULL;
struct blk_plug plug;
int error = 0;
blk_start_plug(&plug);
list_for_each_entry(busyp, &extents->extent_list, list) {
trace_xfs_discard_extent(mp, busyp->agno, busyp->bno,
busyp->length);
error = __blkdev_issue_discard(mp->m_ddev_targp->bt_bdev,
XFS_AGB_TO_DADDR(mp, busyp->agno, busyp->bno),
XFS_FSB_TO_BB(mp, busyp->length),
GFP_KERNEL, &bio);
if (error && error != -EOPNOTSUPP) {
xfs_info(mp,
"discard failed for extent [0x%llx,%u], error %d",
(unsigned long long)busyp->bno,
busyp->length,
error);
break;
}
}
if (bio) {
bio->bi_private = extents;
bio->bi_end_io = xfs_discard_endio;
submit_bio(bio);
} else {
xfs_discard_endio_work(&extents->endio_work);
}
blk_finish_plug(&plug);
return error;
}
struct xfs_trim_cur {
xfs_agblock_t start;
xfs_extlen_t count;
xfs_agblock_t end;
xfs_extlen_t minlen;
bool by_bno;
};
static int
xfs_trim_gather_extents(
struct xfs_perag *pag,
struct xfs_trim_cur *tcur,
struct xfs_busy_extents *extents)
{
struct xfs_mount *mp = pag->pag_mount;
struct xfs_trans *tp;
struct xfs_btree_cur *cur;
struct xfs_buf *agbp;
int error;
int i;
int batch = 100;
/*
* Force out the log. This means any transactions that might have freed
* space before we take the AGF buffer lock are now on disk, and the
* volatile disk cache is flushed.
*/
xfs_log_force(mp, XFS_LOG_SYNC);
error = xfs_trans_alloc_empty(mp, &tp);
if (error)
return error;
error = xfs_alloc_read_agf(pag, tp, 0, &agbp);
if (error)
goto out_trans_cancel;
if (tcur->by_bno) {
/* sub-AG discard request always starts at tcur->start */
cur = xfs_bnobt_init_cursor(mp, tp, agbp, pag);
error = xfs_alloc_lookup_le(cur, tcur->start, 0, &i);
if (!error && !i)
error = xfs_alloc_lookup_ge(cur, tcur->start, 0, &i);
} else if (tcur->start == 0) {
/* first time through a by-len starts with max length */
cur = xfs_cntbt_init_cursor(mp, tp, agbp, pag);
error = xfs_alloc_lookup_ge(cur, 0, tcur->count, &i);
} else {
/* nth time through a by-len starts where we left off */
cur = xfs_cntbt_init_cursor(mp, tp, agbp, pag);
error = xfs_alloc_lookup_le(cur, tcur->start, tcur->count, &i);
}
if (error)
goto out_del_cursor;
if (i == 0) {
/* nothing of that length left in the AG, we are done */
tcur->count = 0;
goto out_del_cursor;
}
/*
* Loop until we are done with all extents that are large
* enough to be worth discarding or we hit batch limits.
*/
while (i) {
xfs_agblock_t fbno;
xfs_extlen_t flen;
error = xfs_alloc_get_rec(cur, &fbno, &flen, &i);
if (error)
break;
if (XFS_IS_CORRUPT(mp, i != 1)) {
xfs_btree_mark_sick(cur);
error = -EFSCORRUPTED;
break;
}
if (--batch <= 0) {
/*
* Update the cursor to point at this extent so we
* restart the next batch from this extent.
*/
tcur->start = fbno;
tcur->count = flen;
break;
}
/*
* If the extent is entirely outside of the range we are
* supposed to skip it. Do not bother to trim down partially
* overlapping ranges for now.
*/
if (fbno + flen < tcur->start) {
trace_xfs_discard_exclude(mp, pag->pag_agno, fbno, flen);
goto next_extent;
}
if (fbno > tcur->end) {
trace_xfs_discard_exclude(mp, pag->pag_agno, fbno, flen);
if (tcur->by_bno) {
tcur->count = 0;
break;
}
goto next_extent;
}
/* Trim the extent returned to the range we want. */
if (fbno < tcur->start) {
flen -= tcur->start - fbno;
fbno = tcur->start;
}
if (fbno + flen > tcur->end + 1)
flen = tcur->end - fbno + 1;
/* Too small? Give up. */
if (flen < tcur->minlen) {
trace_xfs_discard_toosmall(mp, pag->pag_agno, fbno, flen);
if (tcur->by_bno)
goto next_extent;
tcur->count = 0;
break;
}
/*
* If any blocks in the range are still busy, skip the
* discard and try again the next time.
*/
if (xfs_extent_busy_search(mp, pag, fbno, flen)) {
trace_xfs_discard_busy(mp, pag->pag_agno, fbno, flen);
goto next_extent;
}
xfs_extent_busy_insert_discard(pag, fbno, flen,
&extents->extent_list);
next_extent:
if (tcur->by_bno)
error = xfs_btree_increment(cur, 0, &i);
else
error = xfs_btree_decrement(cur, 0, &i);
if (error)
break;
/*
* If there's no more records in the tree, we are done. Set the
* cursor block count to 0 to indicate to the caller that there
* is no more extents to search.
*/
if (i == 0)
tcur->count = 0;
}
/*
* If there was an error, release all the gathered busy extents because
* we aren't going to issue a discard on them any more.
*/
if (error)
xfs_extent_busy_clear(mp, &extents->extent_list, false);
out_del_cursor:
xfs_btree_del_cursor(cur, error);
out_trans_cancel:
xfs_trans_cancel(tp);
return error;
}
static bool
xfs_trim_should_stop(void)
{
return fatal_signal_pending(current) || freezing(current);
}
/*
* Iterate the free list gathering extents and discarding them. We need a cursor
* for the repeated iteration of gather/discard loop, so use the longest extent
* we found in the last batch as the key to start the next.
*/
static int
xfs_trim_perag_extents(
struct xfs_perag *pag,
xfs_agblock_t start,
xfs_agblock_t end,
xfs_extlen_t minlen)
{
struct xfs_trim_cur tcur = {
.start = start,
.count = pag->pagf_longest,
.end = end,
.minlen = minlen,
};
int error = 0;
if (start != 0 || end != pag->block_count)
tcur.by_bno = true;
do {
struct xfs_busy_extents *extents;
extents = kzalloc(sizeof(*extents), GFP_KERNEL);
if (!extents) {
error = -ENOMEM;
break;
}
extents->mount = pag->pag_mount;
extents->owner = extents;
INIT_LIST_HEAD(&extents->extent_list);
error = xfs_trim_gather_extents(pag, &tcur, extents);
if (error) {
kfree(extents);
break;
}
/*
* We hand the extent list to the discard function here so the
* discarded extents can be removed from the busy extent list.
* This allows the discards to run asynchronously with gathering
* the next round of extents to discard.
*
* However, we must ensure that we do not reference the extent
* list after this function call, as it may have been freed by
* the time control returns to us.
*/
error = xfs_discard_extents(pag->pag_mount, extents);
if (error)
break;
if (xfs_trim_should_stop())
break;
} while (tcur.count != 0);
return error;
}
static int
xfs_trim_datadev_extents(
struct xfs_mount *mp,
xfs_daddr_t start,
xfs_daddr_t end,
xfs_extlen_t minlen)
{
xfs_agnumber_t start_agno, end_agno;
xfs_agblock_t start_agbno, end_agbno;
xfs_daddr_t ddev_end;
struct xfs_perag *pag;
int last_error = 0, error;
ddev_end = min_t(xfs_daddr_t, end,
XFS_FSB_TO_BB(mp, mp->m_sb.sb_dblocks) - 1);
start_agno = xfs_daddr_to_agno(mp, start);
start_agbno = xfs_daddr_to_agbno(mp, start);
end_agno = xfs_daddr_to_agno(mp, ddev_end);
end_agbno = xfs_daddr_to_agbno(mp, ddev_end);
for_each_perag_range(mp, start_agno, end_agno, pag) {
xfs_agblock_t agend = pag->block_count;
if (start_agno == end_agno)
agend = end_agbno;
error = xfs_trim_perag_extents(pag, start_agbno, agend, minlen);
if (error)
last_error = error;
if (xfs_trim_should_stop()) {
xfs_perag_rele(pag);
break;
}
start_agbno = 0;
}
return last_error;
}
#ifdef CONFIG_XFS_RT
struct xfs_trim_rtdev {
/* list of rt extents to free */
struct list_head extent_list;
/* minimum length that caller allows us to trim */
xfs_rtblock_t minlen_fsb;
/* restart point for the rtbitmap walk */
xfs_rtxnum_t restart_rtx;
/* stopping point for the current rtbitmap walk */
xfs_rtxnum_t stop_rtx;
};
struct xfs_rtx_busy {
struct list_head list;
xfs_rtblock_t bno;
xfs_rtblock_t length;
};
static void
xfs_discard_free_rtdev_extents(
struct xfs_trim_rtdev *tr)
{
struct xfs_rtx_busy *busyp, *n;
list_for_each_entry_safe(busyp, n, &tr->extent_list, list) {
list_del_init(&busyp->list);
kfree(busyp);
}
}
/*
* Walk the discard list and issue discards on all the busy extents in the
* list. We plug and chain the bios so that we only need a single completion
* call to clear all the busy extents once the discards are complete.
*/
static int
xfs_discard_rtdev_extents(
struct xfs_mount *mp,
struct xfs_trim_rtdev *tr)
{
struct block_device *bdev = mp->m_rtdev_targp->bt_bdev;
struct xfs_rtx_busy *busyp;
struct bio *bio = NULL;
struct blk_plug plug;
xfs_rtblock_t start = NULLRTBLOCK, length = 0;
int error = 0;
blk_start_plug(&plug);
list_for_each_entry(busyp, &tr->extent_list, list) {
if (start == NULLRTBLOCK)
start = busyp->bno;
length += busyp->length;
trace_xfs_discard_rtextent(mp, busyp->bno, busyp->length);
error = __blkdev_issue_discard(bdev,
XFS_FSB_TO_BB(mp, busyp->bno),
XFS_FSB_TO_BB(mp, busyp->length),
GFP_NOFS, &bio);
if (error)
break;
}
xfs_discard_free_rtdev_extents(tr);
if (bio) {
error = submit_bio_wait(bio);
if (error == -EOPNOTSUPP)
error = 0;
if (error)
xfs_info(mp,
"discard failed for rtextent [0x%llx,%llu], error %d",
(unsigned long long)start,
(unsigned long long)length,
error);
bio_put(bio);
}
blk_finish_plug(&plug);
return error;
}
static int
xfs_trim_gather_rtextent(
struct xfs_mount *mp,
struct xfs_trans *tp,
const struct xfs_rtalloc_rec *rec,
void *priv)
{
struct xfs_trim_rtdev *tr = priv;
struct xfs_rtx_busy *busyp;
xfs_rtblock_t rbno, rlen;
if (rec->ar_startext > tr->stop_rtx) {
/*
* If we've scanned a large number of rtbitmap blocks, update
* the cursor to point at this extent so we restart the next
* batch from this extent.
*/
tr->restart_rtx = rec->ar_startext;
return -ECANCELED;
}
rbno = xfs_rtx_to_rtb(mp, rec->ar_startext);
rlen = xfs_rtx_to_rtb(mp, rec->ar_extcount);
/* Ignore too small. */
if (rlen < tr->minlen_fsb) {
trace_xfs_discard_rttoosmall(mp, rbno, rlen);
return 0;
}
busyp = kzalloc(sizeof(struct xfs_rtx_busy), GFP_KERNEL);
if (!busyp)
return -ENOMEM;
busyp->bno = rbno;
busyp->length = rlen;
INIT_LIST_HEAD(&busyp->list);
list_add_tail(&busyp->list, &tr->extent_list);
tr->restart_rtx = rec->ar_startext + rec->ar_extcount;
return 0;
}
static int
xfs_trim_rtdev_extents(
struct xfs_mount *mp,
xfs_daddr_t start,
xfs_daddr_t end,
xfs_daddr_t minlen)
{
struct xfs_trim_rtdev tr = {
.minlen_fsb = XFS_BB_TO_FSB(mp, minlen),
};
xfs_rtxnum_t low, high;
struct xfs_trans *tp;
xfs_daddr_t rtdev_daddr;
int error;
INIT_LIST_HEAD(&tr.extent_list);
/* Shift the start and end downwards to match the rt device. */
rtdev_daddr = XFS_FSB_TO_BB(mp, mp->m_sb.sb_dblocks);
if (start > rtdev_daddr)
start -= rtdev_daddr;
else
start = 0;
if (end <= rtdev_daddr)
return 0;
end -= rtdev_daddr;
error = xfs_trans_alloc_empty(mp, &tp);
if (error)
return error;
end = min_t(xfs_daddr_t, end,
XFS_FSB_TO_BB(mp, mp->m_sb.sb_rblocks) - 1);
/* Convert the rt blocks to rt extents */
low = xfs_rtb_to_rtxup(mp, XFS_BB_TO_FSB(mp, start));
high = xfs_rtb_to_rtx(mp, XFS_BB_TO_FSBT(mp, end));
/*
* Walk the free ranges between low and high. The query_range function
* trims the extents returned.
*/
do {
tr.stop_rtx = low + (mp->m_sb.sb_blocksize * NBBY);
xfs_rtbitmap_lock_shared(mp, XFS_RBMLOCK_BITMAP);
error = xfs_rtalloc_query_range(mp, tp, low, high,
xfs_trim_gather_rtextent, &tr);
if (error == -ECANCELED)
error = 0;
if (error) {
xfs_rtbitmap_unlock_shared(mp, XFS_RBMLOCK_BITMAP);
xfs_discard_free_rtdev_extents(&tr);
break;
}
if (list_empty(&tr.extent_list)) {
xfs_rtbitmap_unlock_shared(mp, XFS_RBMLOCK_BITMAP);
break;
}
error = xfs_discard_rtdev_extents(mp, &tr);
xfs_rtbitmap_unlock_shared(mp, XFS_RBMLOCK_BITMAP);
if (error)
break;
low = tr.restart_rtx;
} while (!xfs_trim_should_stop() && low <= high);
xfs_trans_cancel(tp);
return error;
}
#else
# define xfs_trim_rtdev_extents(...) (-EOPNOTSUPP)
#endif /* CONFIG_XFS_RT */
/*
* trim a range of the filesystem.
*
* Note: the parameters passed from userspace are byte ranges into the
* filesystem which does not match to the format we use for filesystem block
* addressing. FSB addressing is sparse (AGNO|AGBNO), while the incoming format
* is a linear address range. Hence we need to use DADDR based conversions and
* comparisons for determining the correct offset and regions to trim.
*
* The realtime device is mapped into the FITRIM "address space" immediately
* after the data device.
*/
int
xfs_ioc_trim(
struct xfs_mount *mp,
struct fstrim_range __user *urange)
{
unsigned int granularity =
bdev_discard_granularity(mp->m_ddev_targp->bt_bdev);
struct block_device *rt_bdev = NULL;
struct fstrim_range range;
xfs_daddr_t start, end;
xfs_extlen_t minlen;
xfs_rfsblock_t max_blocks;
int error, last_error = 0;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
if (mp->m_rtdev_targp &&
bdev_max_discard_sectors(mp->m_rtdev_targp->bt_bdev))
rt_bdev = mp->m_rtdev_targp->bt_bdev;
if (!bdev_max_discard_sectors(mp->m_ddev_targp->bt_bdev) && !rt_bdev)
return -EOPNOTSUPP;
if (rt_bdev)
granularity = max(granularity,
bdev_discard_granularity(rt_bdev));
/*
* We haven't recovered the log, so we cannot use our bnobt-guided
* storage zapping commands.
*/
if (xfs_has_norecovery(mp))
return -EROFS;
if (copy_from_user(&range, urange, sizeof(range)))
return -EFAULT;
range.minlen = max_t(u64, granularity, range.minlen);
minlen = XFS_B_TO_FSB(mp, range.minlen);
/*
* Truncating down the len isn't actually quite correct, but using
* BBTOB would mean we trivially get overflows for values
* of ULLONG_MAX or slightly lower. And ULLONG_MAX is the default
* used by the fstrim application. In the end it really doesn't
* matter as trimming blocks is an advisory interface.
*/
max_blocks = mp->m_sb.sb_dblocks + mp->m_sb.sb_rblocks;
if (range.start >= XFS_FSB_TO_B(mp, max_blocks) ||
range.minlen > XFS_FSB_TO_B(mp, mp->m_ag_max_usable) ||
range.len < mp->m_sb.sb_blocksize)
return -EINVAL;
start = BTOBB(range.start);
end = start + BTOBBT(range.len) - 1;
if (bdev_max_discard_sectors(mp->m_ddev_targp->bt_bdev)) {
error = xfs_trim_datadev_extents(mp, start, end, minlen);
if (error)
last_error = error;
}
if (rt_bdev && !xfs_trim_should_stop()) {
error = xfs_trim_rtdev_extents(mp, start, end, minlen);
if (error)
last_error = error;
}
if (last_error)
return last_error;
range.len = min_t(unsigned long long, range.len,
XFS_FSB_TO_B(mp, max_blocks) - range.start);
if (copy_to_user(urange, &range, sizeof(range)))
return -EFAULT;
return 0;
}
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