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Date: Thu, 24 Aug 2023 17:26:05 +0800
From: Zhang Yi <yi.zhang@...weicloud.com>
To: linux-ext4@...r.kernel.org
Cc: tytso@....edu, adilger.kernel@...ger.ca, jack@...e.cz,
yi.zhang@...wei.com, yi.zhang@...weicloud.com,
chengzhihao1@...wei.com, yukuai3@...wei.com
Subject: [RFC PATCH 02/16] ext4: make sure allocate pending entry not fail
From: Zhang Yi <yi.zhang@...wei.com>
__insert_pending() allocate memory in atomic context, so the allocation
could fail, but we are not handling that failure now. It could lead
ext4_es_remove_extent() to get wrong reserved clusters, and the global
data blocks reservation count will be incorrect. The same to
extents_status entry preallocation, preallocate pending entry out of the
i_es_lock with __GFP_NOFAIL, make sure __insert_pending() and
__revise_pending() always succeeds.
Signed-off-by: Zhang Yi <yi.zhang@...wei.com>
---
fs/ext4/extents_status.c | 123 ++++++++++++++++++++++++++++-----------
1 file changed, 89 insertions(+), 34 deletions(-)
diff --git a/fs/ext4/extents_status.c b/fs/ext4/extents_status.c
index 5e625ea4545d..f4b50652f0cc 100644
--- a/fs/ext4/extents_status.c
+++ b/fs/ext4/extents_status.c
@@ -152,8 +152,9 @@ static int __es_remove_extent(struct inode *inode, ext4_lblk_t lblk,
static int es_reclaim_extents(struct ext4_inode_info *ei, int *nr_to_scan);
static int __es_shrink(struct ext4_sb_info *sbi, int nr_to_scan,
struct ext4_inode_info *locked_ei);
-static void __revise_pending(struct inode *inode, ext4_lblk_t lblk,
- ext4_lblk_t len);
+static int __revise_pending(struct inode *inode, ext4_lblk_t lblk,
+ ext4_lblk_t len,
+ struct pending_reservation **prealloc);
int __init ext4_init_es(void)
{
@@ -448,6 +449,19 @@ static void ext4_es_list_del(struct inode *inode)
spin_unlock(&sbi->s_es_lock);
}
+static inline struct pending_reservation *__alloc_pending(bool nofail)
+{
+ if (!nofail)
+ return kmem_cache_alloc(ext4_pending_cachep, GFP_ATOMIC);
+
+ return kmem_cache_zalloc(ext4_pending_cachep, GFP_KERNEL | __GFP_NOFAIL);
+}
+
+static inline void __free_pending(struct pending_reservation *pr)
+{
+ kmem_cache_free(ext4_pending_cachep, pr);
+}
+
/*
* Returns true if we cannot fail to allocate memory for this extent_status
* entry and cannot reclaim it until its status changes.
@@ -836,11 +850,12 @@ void ext4_es_insert_extent(struct inode *inode, ext4_lblk_t lblk,
{
struct extent_status newes;
ext4_lblk_t end = lblk + len - 1;
- int err1 = 0;
- int err2 = 0;
+ int err1 = 0, err2 = 0, err3 = 0;
struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
struct extent_status *es1 = NULL;
struct extent_status *es2 = NULL;
+ struct pending_reservation *pr = NULL;
+ bool revise_pending = false;
if (EXT4_SB(inode->i_sb)->s_mount_state & EXT4_FC_REPLAY)
return;
@@ -868,11 +883,17 @@ void ext4_es_insert_extent(struct inode *inode, ext4_lblk_t lblk,
ext4_es_insert_extent_check(inode, &newes);
+ revise_pending = sbi->s_cluster_ratio > 1 &&
+ test_opt(inode->i_sb, DELALLOC) &&
+ (status & (EXTENT_STATUS_WRITTEN |
+ EXTENT_STATUS_UNWRITTEN));
retry:
if (err1 && !es1)
es1 = __es_alloc_extent(true);
if ((err1 || err2) && !es2)
es2 = __es_alloc_extent(true);
+ if ((err1 || err2 || err3) && revise_pending && !pr)
+ pr = __alloc_pending(true);
write_lock(&EXT4_I(inode)->i_es_lock);
err1 = __es_remove_extent(inode, lblk, end, NULL, es1);
@@ -897,13 +918,18 @@ void ext4_es_insert_extent(struct inode *inode, ext4_lblk_t lblk,
es2 = NULL;
}
- if (sbi->s_cluster_ratio > 1 && test_opt(inode->i_sb, DELALLOC) &&
- (status & EXTENT_STATUS_WRITTEN ||
- status & EXTENT_STATUS_UNWRITTEN))
- __revise_pending(inode, lblk, len);
+ if (revise_pending) {
+ err3 = __revise_pending(inode, lblk, len, &pr);
+ if (err3 != 0)
+ goto error;
+ if (pr) {
+ __free_pending(pr);
+ pr = NULL;
+ }
+ }
error:
write_unlock(&EXT4_I(inode)->i_es_lock);
- if (err1 || err2)
+ if (err1 || err2 || err3)
goto retry;
ext4_es_print_tree(inode);
@@ -1311,7 +1337,7 @@ static unsigned int get_rsvd(struct inode *inode, ext4_lblk_t end,
rc->ndelonly--;
node = rb_next(&pr->rb_node);
rb_erase(&pr->rb_node, &tree->root);
- kmem_cache_free(ext4_pending_cachep, pr);
+ __free_pending(pr);
if (!node)
break;
pr = rb_entry(node, struct pending_reservation,
@@ -1907,11 +1933,13 @@ static struct pending_reservation *__get_pending(struct inode *inode,
*
* @inode - file containing the cluster
* @lblk - logical block in the cluster to be added
+ * @prealloc - preallocated pending entry
*
* Returns 0 on successful insertion and -ENOMEM on failure. If the
* pending reservation is already in the set, returns successfully.
*/
-static int __insert_pending(struct inode *inode, ext4_lblk_t lblk)
+static int __insert_pending(struct inode *inode, ext4_lblk_t lblk,
+ struct pending_reservation **prealloc)
{
struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
struct ext4_pending_tree *tree = &EXT4_I(inode)->i_pending_tree;
@@ -1937,10 +1965,15 @@ static int __insert_pending(struct inode *inode, ext4_lblk_t lblk)
}
}
- pr = kmem_cache_alloc(ext4_pending_cachep, GFP_ATOMIC);
- if (pr == NULL) {
- ret = -ENOMEM;
- goto out;
+ if (likely(*prealloc == NULL)) {
+ pr = __alloc_pending(false);
+ if (!pr) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ } else {
+ pr = *prealloc;
+ *prealloc = NULL;
}
pr->lclu = lclu;
@@ -1970,7 +2003,7 @@ static void __remove_pending(struct inode *inode, ext4_lblk_t lblk)
if (pr != NULL) {
tree = &EXT4_I(inode)->i_pending_tree;
rb_erase(&pr->rb_node, &tree->root);
- kmem_cache_free(ext4_pending_cachep, pr);
+ __free_pending(pr);
}
}
@@ -2029,10 +2062,10 @@ void ext4_es_insert_delayed_block(struct inode *inode, ext4_lblk_t lblk,
bool allocated)
{
struct extent_status newes;
- int err1 = 0;
- int err2 = 0;
+ int err1 = 0, err2 = 0, err3 = 0;
struct extent_status *es1 = NULL;
struct extent_status *es2 = NULL;
+ struct pending_reservation *pr = NULL;
if (EXT4_SB(inode->i_sb)->s_mount_state & EXT4_FC_REPLAY)
return;
@@ -2052,6 +2085,8 @@ void ext4_es_insert_delayed_block(struct inode *inode, ext4_lblk_t lblk,
es1 = __es_alloc_extent(true);
if ((err1 || err2) && !es2)
es2 = __es_alloc_extent(true);
+ if ((err1 || err2 || err3) && allocated && !pr)
+ pr = __alloc_pending(true);
write_lock(&EXT4_I(inode)->i_es_lock);
err1 = __es_remove_extent(inode, lblk, lblk, NULL, es1);
@@ -2074,11 +2109,18 @@ void ext4_es_insert_delayed_block(struct inode *inode, ext4_lblk_t lblk,
es2 = NULL;
}
- if (allocated)
- __insert_pending(inode, lblk);
+ if (allocated) {
+ err3 = __insert_pending(inode, lblk, &pr);
+ if (err3 != 0)
+ goto error;
+ if (pr) {
+ __free_pending(pr);
+ pr = NULL;
+ }
+ }
error:
write_unlock(&EXT4_I(inode)->i_es_lock);
- if (err1 || err2)
+ if (err1 || err2 || err3)
goto retry;
ext4_es_print_tree(inode);
@@ -2184,21 +2226,24 @@ unsigned int ext4_es_delayed_clu(struct inode *inode, ext4_lblk_t lblk,
* @inode - file containing the range
* @lblk - logical block defining the start of range
* @len - length of range in blocks
+ * @prealloc - preallocated pending entry
*
* Used after a newly allocated extent is added to the extents status tree.
* Requires that the extents in the range have either written or unwritten
* status. Must be called while holding i_es_lock.
*/
-static void __revise_pending(struct inode *inode, ext4_lblk_t lblk,
- ext4_lblk_t len)
+static int __revise_pending(struct inode *inode, ext4_lblk_t lblk,
+ ext4_lblk_t len,
+ struct pending_reservation **prealloc)
{
struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
ext4_lblk_t end = lblk + len - 1;
ext4_lblk_t first, last;
bool f_del = false, l_del = false;
+ int ret = 0;
if (len == 0)
- return;
+ return 0;
/*
* Two cases - block range within single cluster and block range
@@ -2219,7 +2264,9 @@ static void __revise_pending(struct inode *inode, ext4_lblk_t lblk,
f_del = __es_scan_range(inode, &ext4_es_is_delonly,
first, lblk - 1);
if (f_del) {
- __insert_pending(inode, first);
+ ret = __insert_pending(inode, first, prealloc);
+ if (ret < 0)
+ goto out;
} else {
last = EXT4_LBLK_CMASK(sbi, end) +
sbi->s_cluster_ratio - 1;
@@ -2227,9 +2274,11 @@ static void __revise_pending(struct inode *inode, ext4_lblk_t lblk,
l_del = __es_scan_range(inode,
&ext4_es_is_delonly,
end + 1, last);
- if (l_del)
- __insert_pending(inode, last);
- else
+ if (l_del) {
+ ret = __insert_pending(inode, last, prealloc);
+ if (ret < 0)
+ goto out;
+ } else
__remove_pending(inode, last);
}
} else {
@@ -2237,18 +2286,24 @@ static void __revise_pending(struct inode *inode, ext4_lblk_t lblk,
if (first != lblk)
f_del = __es_scan_range(inode, &ext4_es_is_delonly,
first, lblk - 1);
- if (f_del)
- __insert_pending(inode, first);
- else
+ if (f_del) {
+ ret = __insert_pending(inode, first, prealloc);
+ if (ret < 0)
+ goto out;
+ } else
__remove_pending(inode, first);
last = EXT4_LBLK_CMASK(sbi, end) + sbi->s_cluster_ratio - 1;
if (last != end)
l_del = __es_scan_range(inode, &ext4_es_is_delonly,
end + 1, last);
- if (l_del)
- __insert_pending(inode, last);
- else
+ if (l_del) {
+ ret = __insert_pending(inode, last, prealloc);
+ if (ret < 0)
+ goto out;
+ } else
__remove_pending(inode, last);
}
+out:
+ return ret;
}
--
2.39.2
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