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Message-Id: <20200507175028.15061-1-pendleton@google.com>
Date: Thu, 7 May 2020 10:50:28 -0700
From: Anna Pendleton <pendleton@...gle.com>
To: "Theodore Ts'o" <tytso@....edu>,
Andreas Dilger <adilger.kernel@...ger.ca>
Cc: linux-ext4@...r.kernel.org, Anna Pendleton <pendleton@...gle.com>,
Harshad Shirwadkar <harshadshirwadkar@...il.com>
Subject: [PATCH] ext4: avoid ext4_error()'s caused by ENOMEM in the truncate path
From: Theodore Ts'o <tytso@....edu>
We can't fail in the truncate path without requiring an fsck.
Add work around for this by using a combination of retry loops
and the __GFP_NOFAIL flag.
From: Theodore Ts'o <tytso@....edu>
Signed-off-by: Theodore Ts'o <tytso@....edu>
Signed-off-by: Anna Pendleton <pendleton@...gle.com>
Reviewed-by: Harshad Shirwadkar <harshadshirwadkar@...il.com>
---
fs/ext4/ext4.h | 1 +
fs/ext4/extents.c | 43 +++++++++++++++++++++++++++++++++----------
2 files changed, 34 insertions(+), 10 deletions(-)
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 91eb4381cae5..af010f5009e4 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -632,6 +632,7 @@ enum {
*/
#define EXT4_EX_NOCACHE 0x40000000
#define EXT4_EX_FORCE_CACHE 0x20000000
+#define EXT4_EX_NOFAIL 0x10000000
/*
* Flags used by ext4_free_blocks
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index f2b577b315a0..c2f665f8109e 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -297,11 +297,14 @@ ext4_force_split_extent_at(handle_t *handle, struct inode *inode,
{
struct ext4_ext_path *path = *ppath;
int unwritten = ext4_ext_is_unwritten(path[path->p_depth].p_ext);
+ int flags = EXT4_EX_NOCACHE | EXT4_GET_BLOCKS_PRE_IO;
+
+ if (nofail)
+ flags |= EXT4_GET_BLOCKS_METADATA_NOFAIL | EXT4_EX_NOFAIL;
return ext4_split_extent_at(handle, inode, ppath, lblk, unwritten ?
EXT4_EXT_MARK_UNWRIT1|EXT4_EXT_MARK_UNWRIT2 : 0,
- EXT4_EX_NOCACHE | EXT4_GET_BLOCKS_PRE_IO |
- (nofail ? EXT4_GET_BLOCKS_METADATA_NOFAIL:0));
+ flags);
}
static int
@@ -487,8 +490,12 @@ __read_extent_tree_block(const char *function, unsigned int line,
{
struct buffer_head *bh;
int err;
+ int gfp_flags = __GFP_MOVABLE | GFP_NOFS;
+
+ if (flags & EXT4_EX_NOFAIL)
+ gfp_flags |= __GFP_NOFAIL;
- bh = sb_getblk_gfp(inode->i_sb, pblk, __GFP_MOVABLE | GFP_NOFS);
+ bh = sb_getblk_gfp(inode->i_sb, pblk, gfp_flags);
if (unlikely(!bh))
return ERR_PTR(-ENOMEM);
@@ -838,6 +845,10 @@ ext4_find_extent(struct inode *inode, ext4_lblk_t block,
struct ext4_ext_path *path = orig_path ? *orig_path : NULL;
short int depth, i, ppos = 0;
int ret;
+ int gfp_flags = GFP_NOFS;
+
+ if (flags & EXT4_EX_NOFAIL)
+ gfp_flags |= __GFP_NOFAIL;
eh = ext_inode_hdr(inode);
depth = ext_depth(inode);
@@ -858,7 +869,7 @@ ext4_find_extent(struct inode *inode, ext4_lblk_t block,
if (!path) {
/* account possible depth increase */
path = kcalloc(depth + 2, sizeof(struct ext4_ext_path),
- GFP_NOFS);
+ gfp_flags);
if (unlikely(!path))
return ERR_PTR(-ENOMEM);
path[0].p_maxdepth = depth + 1;
@@ -1008,9 +1019,13 @@ static int ext4_ext_split(handle_t *handle, struct inode *inode,
ext4_fsblk_t newblock, oldblock;
__le32 border;
ext4_fsblk_t *ablocks = NULL; /* array of allocated blocks */
+ int gfp_flags = GFP_NOFS;
int err = 0;
size_t ext_size = 0;
+ if (flags & EXT4_EX_NOFAIL)
+ gfp_flags |= __GFP_NOFAIL;
+
/* make decision: where to split? */
/* FIXME: now decision is simplest: at current extent */
@@ -1044,7 +1059,7 @@ static int ext4_ext_split(handle_t *handle, struct inode *inode,
* We need this to handle errors and free blocks
* upon them.
*/
- ablocks = kcalloc(depth, sizeof(ext4_fsblk_t), GFP_NOFS);
+ ablocks = kcalloc(depth, sizeof(ext4_fsblk_t), gfp_flags);
if (!ablocks)
return -ENOMEM;
@@ -2020,7 +2035,7 @@ int ext4_ext_insert_extent(handle_t *handle, struct inode *inode,
if (next != EXT_MAX_BLOCKS) {
ext_debug("next leaf block - %u\n", next);
BUG_ON(npath != NULL);
- npath = ext4_find_extent(inode, next, NULL, 0);
+ npath = ext4_find_extent(inode, next, NULL, gb_flags);
if (IS_ERR(npath))
return PTR_ERR(npath);
BUG_ON(npath->p_depth != path->p_depth);
@@ -2793,7 +2808,8 @@ int ext4_ext_remove_space(struct inode *inode, ext4_lblk_t start,
ext4_fsblk_t pblk;
/* find extent for or closest extent to this block */
- path = ext4_find_extent(inode, end, NULL, EXT4_EX_NOCACHE);
+ path = ext4_find_extent(inode, end, NULL,
+ EXT4_EX_NOCACHE | EXT4_EX_NOFAIL);
if (IS_ERR(path)) {
ext4_journal_stop(handle);
return PTR_ERR(path);
@@ -2879,7 +2895,7 @@ int ext4_ext_remove_space(struct inode *inode, ext4_lblk_t start,
le16_to_cpu(path[k].p_hdr->eh_entries)+1;
} else {
path = kcalloc(depth + 1, sizeof(struct ext4_ext_path),
- GFP_NOFS);
+ GFP_NOFS | __GFP_NOFAIL);
if (path == NULL) {
ext4_journal_stop(handle);
return -ENOMEM;
@@ -3300,7 +3316,7 @@ static int ext4_split_extent(handle_t *handle,
* Update path is required because previous ext4_split_extent_at() may
* result in split of original leaf or extent zeroout.
*/
- path = ext4_find_extent(inode, map->m_lblk, ppath, 0);
+ path = ext4_find_extent(inode, map->m_lblk, ppath, flags);
if (IS_ERR(path))
return PTR_ERR(path);
depth = ext_depth(inode);
@@ -4353,7 +4369,14 @@ int ext4_ext_truncate(handle_t *handle, struct inode *inode)
}
if (err)
return err;
- return ext4_ext_remove_space(inode, last_block, EXT_MAX_BLOCKS - 1);
+retry_remove_space:
+ err = ext4_ext_remove_space(inode, last_block, EXT_MAX_BLOCKS - 1);
+ if (err == -ENOMEM) {
+ cond_resched();
+ congestion_wait(BLK_RW_ASYNC, HZ/50);
+ goto retry_remove_space;
+ }
+ return err;
}
static int ext4_alloc_file_blocks(struct file *file, ext4_lblk_t offset,
--
2.26.2.526.g744177e7f7-goog
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