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Message-ID: <19879dd3-58dc-3fc0-9d9f-e6e343a59dc3@gmail.com>
Date: Fri, 24 Jul 2020 10:58:15 +0800
From: brookxu <brookxu.cn@...il.com>
To: tytso@....edu, adilger.kernel@...ger.ca,
linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 2/3] ext4: limit the length of per-inode prealloc list
In the scenario of writing sparse files, the Per-inode prealloc list may
be very long, resulting in high overhead for ext4_mb_use_preallocated().
To circumvent this problem, we limit the maximum length of per-inode
prealloc list to 512 and allow users to modify it.
Signed-off-by: Chunguang Xu <brookxu@...cent.com>
---
fs/ext4/ext4.h | 3 ++-
fs/ext4/extents.c | 10 ++++-----
fs/ext4/file.c | 2 +-
fs/ext4/indirect.c | 2 +-
fs/ext4/inode.c | 6 +++---
fs/ext4/ioctl.c | 2 +-
fs/ext4/mballoc.c | 57 +++++++++++++++++++++++++++++++++++++++++++++++----
fs/ext4/mballoc.h | 4 ++++
fs/ext4/move_extent.c | 4 ++--
fs/ext4/super.c | 2 +-
fs/ext4/sysfs.c | 2 ++
11 files changed, 75 insertions(+), 19 deletions(-)
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 42f5060..68e0ebe 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1501,6 +1501,7 @@ struct ext4_sb_info {
unsigned int s_mb_stats;
unsigned int s_mb_order2_reqs;
unsigned int s_mb_group_prealloc;
+ unsigned int s_mb_max_inode_prealloc;
unsigned int s_max_dir_size_kb;
/* where last allocation was done - for stream allocation */
unsigned long s_mb_last_group;
@@ -2651,7 +2652,7 @@ extern int ext4_init_inode_table(struct super_block *sb,
extern ext4_fsblk_t ext4_mb_new_blocks(handle_t *,
struct ext4_allocation_request *, int *);
extern int ext4_mb_reserve_blocks(struct super_block *, int);
-extern void ext4_discard_preallocations(struct inode *);
+extern void ext4_discard_preallocations(struct inode *, unsigned int);
extern int __init ext4_init_mballoc(void);
extern void ext4_exit_mballoc(void);
extern void ext4_free_blocks(handle_t *handle, struct inode *inode,
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 221f240..a40f928 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -100,7 +100,7 @@ static int ext4_ext_trunc_restart_fn(struct inode *inode, int *dropped)
* i_mutex. So we can safely drop the i_data_sem here.
*/
BUG_ON(EXT4_JOURNAL(inode) == NULL);
- ext4_discard_preallocations(inode);
+ ext4_discard_preallocations(inode, 0);
up_write(&EXT4_I(inode)->i_data_sem);
*dropped = 1;
return 0;
@@ -4272,7 +4272,7 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
* not a good idea to call discard here directly,
* but otherwise we'd need to call it every free().
*/
- ext4_discard_preallocations(inode);
+ ext4_discard_preallocations(inode, 0);
if (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE)
fb_flags = EXT4_FREE_BLOCKS_NO_QUOT_UPDATE;
ext4_free_blocks(handle, inode, NULL, newblock,
@@ -5299,7 +5299,7 @@ static int ext4_collapse_range(struct inode *inode, loff_t offset, loff_t len)
}
down_write(&EXT4_I(inode)->i_data_sem);
- ext4_discard_preallocations(inode);
+ ext4_discard_preallocations(inode, 0);
ret = ext4_es_remove_extent(inode, punch_start,
EXT_MAX_BLOCKS - punch_start);
@@ -5313,7 +5313,7 @@ static int ext4_collapse_range(struct inode *inode, loff_t offset, loff_t len)
up_write(&EXT4_I(inode)->i_data_sem);
goto out_stop;
}
- ext4_discard_preallocations(inode);
+ ext4_discard_preallocations(inode, 0);
ret = ext4_ext_shift_extents(inode, handle, punch_stop,
punch_stop - punch_start, SHIFT_LEFT);
@@ -5445,7 +5445,7 @@ static int ext4_insert_range(struct inode *inode, loff_t offset, loff_t len)
goto out_stop;
down_write(&EXT4_I(inode)->i_data_sem);
- ext4_discard_preallocations(inode);
+ ext4_discard_preallocations(inode, 0);
path = ext4_find_extent(inode, offset_lblk, NULL, 0);
if (IS_ERR(path)) {
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 2a01e31..e3ab8ea 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -148,7 +148,7 @@ static int ext4_release_file(struct inode *inode, struct file *filp)
!EXT4_I(inode)->i_reserved_data_blocks)
{
down_write(&EXT4_I(inode)->i_data_sem);
- ext4_discard_preallocations(inode);
+ ext4_discard_preallocations(inode, 0);
up_write(&EXT4_I(inode)->i_data_sem);
}
if (is_dx(inode) && filp->private_data)
diff --git a/fs/ext4/indirect.c b/fs/ext4/indirect.c
index be2b66e..ec6b930 100644
--- a/fs/ext4/indirect.c
+++ b/fs/ext4/indirect.c
@@ -696,7 +696,7 @@ static int ext4_ind_trunc_restart_fn(handle_t *handle, struct inode *inode,
* i_mutex. So we can safely drop the i_data_sem here.
*/
BUG_ON(EXT4_JOURNAL(inode) == NULL);
- ext4_discard_preallocations(inode);
+ ext4_discard_preallocations(inode, 0);
up_write(&EXT4_I(inode)->i_data_sem);
*dropped = 1;
return 0;
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 10dd470..bb9e1cd 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -383,7 +383,7 @@ void ext4_da_update_reserve_space(struct inode *inode,
*/
if ((ei->i_reserved_data_blocks == 0) &&
!inode_is_open_for_write(inode))
- ext4_discard_preallocations(inode);
+ ext4_discard_preallocations(inode, 0);
}
static int __check_block_validity(struct inode *inode, const char *func,
@@ -4056,7 +4056,7 @@ int ext4_punch_hole(struct inode *inode, loff_t offset, loff_t length)
if (stop_block > first_block) {
down_write(&EXT4_I(inode)->i_data_sem);
- ext4_discard_preallocations(inode);
+ ext4_discard_preallocations(inode, 0);
ret = ext4_es_remove_extent(inode, first_block,
stop_block - first_block);
@@ -4211,7 +4211,7 @@ int ext4_truncate(struct inode *inode)
down_write(&EXT4_I(inode)->i_data_sem);
- ext4_discard_preallocations(inode);
+ ext4_discard_preallocations(inode, 0);
if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
err = ext4_ext_truncate(handle, inode);
diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index 999cf6a..a5fcc23 100644
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -202,7 +202,7 @@ static long swap_inode_boot_loader(struct super_block *sb,
reset_inode_seed(inode);
reset_inode_seed(inode_bl);
- ext4_discard_preallocations(inode);
+ ext4_discard_preallocations(inode, 0);
err = ext4_mark_inode_dirty(handle, inode);
if (err < 0) {
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 4f21f34..28a139f 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -2736,6 +2736,7 @@ int ext4_mb_init(struct super_block *sb)
sbi->s_mb_stats = MB_DEFAULT_STATS;
sbi->s_mb_stream_request = MB_DEFAULT_STREAM_THRESHOLD;
sbi->s_mb_order2_reqs = MB_DEFAULT_ORDER2_REQS;
+ sbi->s_mb_max_inode_prealloc = MB_DEFAULT_MAX_INODE_PREALLOC;
/*
* The default group preallocation is 512, which for 4k block
* sizes translates to 2 megabytes. However for bigalloc file
@@ -4103,7 +4104,7 @@ static void ext4_mb_new_preallocation(struct ext4_allocation_context *ac)
*
* FIXME!! Make sure it is valid at all the call sites
*/
-void ext4_discard_preallocations(struct inode *inode)
+void ext4_discard_preallocations(struct inode *inode, unsigned int needed)
{
struct ext4_inode_info *ei = EXT4_I(inode);
struct super_block *sb = inode->i_sb;
@@ -4121,15 +4122,18 @@ void ext4_discard_preallocations(struct inode *inode)
mb_debug(sb, "discard preallocation for inode %lu\n",
inode->i_ino);
- trace_ext4_discard_preallocations(inode);
+ trace_ext4_discard_preallocations(inode, needed);
INIT_LIST_HEAD(&list);
+ if (needed == 0)
+ needed = UINT_MAX;
+
repeat:
/* first, collect all pa's in the inode */
spin_lock(&ei->i_prealloc_lock);
- while (!list_empty(&ei->i_prealloc_list)) {
- pa = list_entry(ei->i_prealloc_list.next,
+ while (!list_empty(&ei->i_prealloc_list) && needed) {
+ pa = list_entry(ei->i_prealloc_list.prev,
struct ext4_prealloc_space, pa_inode_list);
BUG_ON(pa->pa_obj_lock != &ei->i_prealloc_lock);
spin_lock(&pa->pa_lock);
@@ -4150,6 +4154,7 @@ void ext4_discard_preallocations(struct inode *inode)
spin_unlock(&pa->pa_lock);
list_del_rcu(&pa->pa_inode_list);
list_add(&pa->u.pa_tmp_list, &list);
+ needed--;
continue;
}
@@ -4549,10 +4554,42 @@ static void ext4_mb_add_n_trim(struct ext4_allocation_context *ac)
}
/*
+ * if per-inode prealloc list is too long, trim some PA
+ */
+static void
+ext4_mb_trim_inode_pa(struct inode *inode)
+{
+ struct ext4_inode_info *ei = EXT4_I(inode);
+ struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+ struct ext4_prealloc_space *pa;
+ int count = 0, delta;
+
+ rcu_read_lock();
+ list_for_each_entry_rcu(pa, &ei->i_prealloc_list, pa_inode_list) {
+ spin_lock(&pa->pa_lock);
+ if (pa->pa_deleted) {
+ spin_unlock(&pa->pa_lock);
+ continue;
+ }
+ count++;
+ spin_unlock(&pa->pa_lock);
+ }
+ rcu_read_unlock();
+
+ delta = (sbi->s_mb_max_inode_prealloc >> 2) + 1;
+ if (count > sbi->s_mb_max_inode_prealloc + delta) {
+ count -= sbi->s_mb_max_inode_prealloc;
+ ext4_discard_preallocations(inode, count);
+ }
+}
+
+/*
* release all resource we used in allocation
*/
static int ext4_mb_release_context(struct ext4_allocation_context *ac)
{
+ struct inode *inode = ac->ac_inode;
+ struct ext4_inode_info *ei = EXT4_I(inode);
struct ext4_sb_info *sbi = EXT4_SB(ac->ac_sb);
struct ext4_prealloc_space *pa = ac->ac_pa;
if (pa) {
@@ -4578,6 +4615,17 @@ static int ext4_mb_release_context(struct ext4_allocation_context *ac)
ext4_mb_add_n_trim(ac);
}
}
+
+ if (pa->pa_type == MB_INODE_PA) {
+ /*
+ * treat per-inode prealloc list as a lru list, then try
+ * to trim the least recently used PA.
+ */
+ spin_lock(pa->pa_obj_lock);
+ list_move(&ei->i_prealloc_list, &pa->pa_inode_list);
+ spin_unlock(pa->pa_obj_lock);
+ }
+
ext4_mb_put_pa(ac, ac->ac_sb, pa);
}
if (ac->ac_bitmap_page)
@@ -4587,6 +4635,7 @@ static int ext4_mb_release_context(struct ext4_allocation_context *ac)
if (ac->ac_flags & EXT4_MB_HINT_GROUP_ALLOC)
mutex_unlock(&ac->ac_lg->lg_mutex);
ext4_mb_collect_stats(ac);
+ ext4_mb_trim_inode_pa(inode);
return 0;
}
diff --git a/fs/ext4/mballoc.h b/fs/ext4/mballoc.h
index 6b4d17c..e75b474 100644
--- a/fs/ext4/mballoc.h
+++ b/fs/ext4/mballoc.h
@@ -73,6 +73,10 @@
*/
#define MB_DEFAULT_GROUP_PREALLOC 512
+/*
+ * maximum length of inode prealloc list
+ */
+#define MB_DEFAULT_MAX_INODE_PREALLOC 512
struct ext4_free_data {
/* this links the free block information from sb_info */
diff --git a/fs/ext4/move_extent.c b/fs/ext4/move_extent.c
index 1ed86fb..0d601b8 100644
--- a/fs/ext4/move_extent.c
+++ b/fs/ext4/move_extent.c
@@ -686,8 +686,8 @@
out:
if (*moved_len) {
- ext4_discard_preallocations(orig_inode);
- ext4_discard_preallocations(donor_inode);
+ ext4_discard_preallocations(orig_inode, 0);
+ ext4_discard_preallocations(donor_inode, 0);
}
ext4_ext_drop_refs(path);
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 330957e..8ce61f3 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1216,7 +1216,7 @@ void ext4_clear_inode(struct inode *inode)
{
invalidate_inode_buffers(inode);
clear_inode(inode);
- ext4_discard_preallocations(inode);
+ ext4_discard_preallocations(inode, 0);
ext4_es_remove_extent(inode, 0, EXT_MAX_BLOCKS);
dquot_drop(inode);
if (EXT4_I(inode)->jinode) {
diff --git a/fs/ext4/sysfs.c b/fs/ext4/sysfs.c
index 6c9fc9e..92f04e9 100644
--- a/fs/ext4/sysfs.c
+++ b/fs/ext4/sysfs.c
@@ -215,6 +215,7 @@ static ssize_t journal_task_show(struct ext4_sb_info *sbi, char *buf)
EXT4_RW_ATTR_SBI_UI(mb_order2_req, s_mb_order2_reqs);
EXT4_RW_ATTR_SBI_UI(mb_stream_req, s_mb_stream_request);
EXT4_RW_ATTR_SBI_UI(mb_group_prealloc, s_mb_group_prealloc);
+EXT4_RW_ATTR_SBI_UI(mb_max_inode_prealloc, s_mb_max_inode_prealloc);
EXT4_RW_ATTR_SBI_UI(extent_max_zeroout_kb, s_extent_max_zeroout_kb);
EXT4_ATTR(trigger_fs_error, 0200, trigger_test_error);
EXT4_RW_ATTR_SBI_UI(err_ratelimit_interval_ms, s_err_ratelimit_state.interval);
@@ -257,6 +258,7 @@ static ssize_t journal_task_show(struct ext4_sb_info *sbi, char *buf)
ATTR_LIST(mb_order2_req),
ATTR_LIST(mb_stream_req),
ATTR_LIST(mb_group_prealloc),
+ ATTR_LIST(mb_max_inode_prealloc),
ATTR_LIST(max_writeback_mb_bump),
ATTR_LIST(extent_max_zeroout_kb),
ATTR_LIST(trigger_fs_error),
--
1.8.3.1
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