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f2fs: Fix deadlock in f2fs_gc() context during atomic files handling 

[ Upstream commit 677017d196 ]

The FS got stuck in the below stack when the storage is almost
full/dirty condition (when FG_GC is being done).

schedule_timeout
io_schedule_timeout
congestion_wait
f2fs_drop_inmem_pages_all
f2fs_gc
f2fs_balance_fs
__write_node_page
f2fs_fsync_node_pages
f2fs_do_sync_file
f2fs_ioctl

The root cause for this issue is there is a potential infinite loop
in f2fs_drop_inmem_pages_all() for the case where gc_failure is true
and when there an inode whose i_gc_failures[GC_FAILURE_ATOMIC] is
not set. Fix this by keeping track of the total atomic files
currently opened and using that to exit from this condition.

Fix-suggested-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Sahitya Tummala <stummala@codeaurora.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
5.4-rM2-2.2.x-imx-squashed
Sahitya Tummala 2019-11-13 16:01:03 +05:30 committed by Greg Kroah-Hartman
parent ddf426dbe3
commit ce72694970
3 changed files with 17 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
fs/f2fs/f2fs.h
View File

@ -1289,6 +1289,7 @@ struct f2fs_sb_info {
unsigned int gc_mode; /* current GC state */
unsigned int next_victim_seg[2]; /* next segment in victim section */
/* for skip statistic */
unsigned int atomic_files; /* # of opened atomic file */
unsigned long long skipped_atomic_files[2]; /* FG_GC and BG_GC */
unsigned long long skipped_gc_rwsem; /* FG_GC only */

1
fs/f2fs/file.c
View File

@ -1890,6 +1890,7 @@ static int f2fs_ioc_start_atomic_write(struct file *filp)
spin_lock(&sbi->inode_lock[ATOMIC_FILE]);
if (list_empty(&fi->inmem_ilist))
list_add_tail(&fi->inmem_ilist, &sbi->inode_list[ATOMIC_FILE]);
sbi->atomic_files++;
spin_unlock(&sbi->inode_lock[ATOMIC_FILE]);
/* add inode in inmem_list first and set atomic_file */

21
fs/f2fs/segment.c
View File

@ -288,6 +288,8 @@ void f2fs_drop_inmem_pages_all(struct f2fs_sb_info *sbi, bool gc_failure)
struct list_head *head = &sbi->inode_list[ATOMIC_FILE];
struct inode *inode;
struct f2fs_inode_info *fi;
unsigned int count = sbi->atomic_files;
unsigned int looped = 0;
next:
spin_lock(&sbi->inode_lock[ATOMIC_FILE]);
if (list_empty(head)) {
@ -296,22 +298,26 @@ next:
}
fi = list_first_entry(head, struct f2fs_inode_info, inmem_ilist);
inode = igrab(&fi->vfs_inode);
if (inode)
list_move_tail(&fi->inmem_ilist, head);
spin_unlock(&sbi->inode_lock[ATOMIC_FILE]);
if (inode) {
if (gc_failure) {
if (fi->i_gc_failures[GC_FAILURE_ATOMIC])
goto drop;
goto skip;
if (!fi->i_gc_failures[GC_FAILURE_ATOMIC])
goto skip;
}
drop:
set_inode_flag(inode, FI_ATOMIC_REVOKE_REQUEST);
f2fs_drop_inmem_pages(inode);
skip:
iput(inode);
}
skip:
congestion_wait(BLK_RW_ASYNC, HZ/50);
cond_resched();
if (gc_failure) {
if (++looped >= count)
return;
}
goto next;
}
@ -327,13 +333,16 @@ void f2fs_drop_inmem_pages(struct inode *inode)
mutex_unlock(&fi->inmem_lock);
}
clear_inode_flag(inode, FI_ATOMIC_FILE);
fi->i_gc_failures[GC_FAILURE_ATOMIC] = 0;
stat_dec_atomic_write(inode);
spin_lock(&sbi->inode_lock[ATOMIC_FILE]);
if (!list_empty(&fi->inmem_ilist))
list_del_init(&fi->inmem_ilist);
if (f2fs_is_atomic_file(inode)) {
clear_inode_flag(inode, FI_ATOMIC_FILE);
sbi->atomic_files--;
}
spin_unlock(&sbi->inode_lock[ATOMIC_FILE]);
}