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ext4: avoid ext4_error()'s caused by ENOMEM in the truncate path

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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@mit.edu>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Anna Pendleton <pendleton@google.com>
Reviewed-by: Harshad Shirwadkar <harshadshirwadkar@gmail.com>
Link: https://lore.kernel.org/r/20200507175028.15061-1-pendleton@google.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Theodore Ts'o 2020-05-07 10:50:28 -07:00
parent 08adf452e6
commit 73c384c0cd
2 changed files with 34 additions and 10 deletions
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1
fs/ext4/ext4.h
View File

@ -630,6 +630,7 @@ enum {
*/
#define EXT4_EX_NOCACHE 0x40000000
#define EXT4_EX_FORCE_CACHE 0x20000000
#define EXT4_EX_NOFAIL 0x10000000
/*
* Flags used by ext4_free_blocks

43
fs/ext4/extents.c
View File

@ -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;
gfp_t gfp_flags = __GFP_MOVABLE | GFP_NOFS;
bh = sb_getblk_gfp(inode->i_sb, pblk, __GFP_MOVABLE | GFP_NOFS);
if (flags & EXT4_EX_NOFAIL)
gfp_flags |= __GFP_NOFAIL;
bh = sb_getblk_gfp(inode->i_sb, pblk, gfp_flags);
if (unlikely(!bh))
return ERR_PTR(-ENOMEM);
@ -837,6 +844,10 @@ 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;
gfp_t gfp_flags = GFP_NOFS;
if (flags & EXT4_EX_NOFAIL)
gfp_flags |= __GFP_NOFAIL;
eh = ext_inode_hdr(inode);
depth = ext_depth(inode);
@ -857,7 +868,7 @@ 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;
@ -1007,9 +1018,13 @@ 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 */
gfp_t 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 */
@ -1043,7 +1058,7 @@ 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;
@ -2019,7 +2034,7 @@ prepend:
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);
@ -2792,7 +2807,8 @@ again:
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);
@ -2878,7 +2894,7 @@ again:
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;
@ -3303,7 +3319,7 @@ 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);
@ -4365,7 +4381,14 @@ retry:
}
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,