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FAILED: patch "[PATCH] ext4: make sure allocate pending entry not fail" failed to apply to 6.1-stable tree

PATCH [email protected] 1 participant 1 message Nov 24, 2023

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The patch below does not apply to the 6.1-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y
git checkout FETCH_HEAD
git cherry-pick -x 8e387c89e96b9543a339f84043cf9df15fed2632
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2023112431-sniff-afford-8ceb@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^..

Possible dependencies:

8e387c89e96b ("ext4: make sure allocate pending entry not fail") 768d612f7982 ("ext4: fix slab-use-after-free in ext4_es_insert_extent()") 2a69c450083d ("ext4: using nofail preallocation in ext4_es_insert_extent()") 4a2d98447b37 ("ext4: using nofail preallocation in ext4_es_insert_delayed_block()") e9fe2b882bd5 ("ext4: using nofail preallocation in ext4_es_remove_extent()") bda3efaf774f ("ext4: use pre-allocated es in __es_remove_extent()") 95f0b320339a ("ext4: use pre-allocated es in __es_insert_extent()") 73a2f033656b ("ext4: factor out __es_alloc_extent() and __es_free_extent()") 9649eb18c628 ("ext4: add a new helper to check if es must be kept")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 8e387c89e96b9543a339f84043cf9df15fed2632 Mon Sep 17 00:00:00 2001
From: Zhang Yi <[email protected]>
Date: Thu, 24 Aug 2023 17:26:05 +0800
Subject: [PATCH] ext4: make sure allocate pending entry not fail

__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 <[email protected]>
Cc [email protected]
Link https://lore.kernel.org/r/[email protected] open here
Reviewed-by Jan Kara <[email protected]>
Signed-off-by Theodore Ts'o <[email protected]>
fs/ext4/extents_status.c +89 -34
index 5e625ea4545d..f4b50652f0cc 100644
@@ -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;
 }