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Commit dd9d552f authored by Sayali Lokhande's avatar Sayali Lokhande
Browse files

f2fs: avoid infinite GC loop due to stale atomic files 



If committing atomic pages is failed when doing f2fs_do_sync_file(), we can
get committed pages but atomic_file being still set like:

- inmem:    0, atomic IO:    4 (Max.   10), volatile IO:    0 (Max.    0)

If GC selects this block, we can get an infinite loop like this:

f2fs_submit_page_bio: dev = (253,7), ino = 2, page_index = 0x2359a8,
  oldaddr = 0x2359a8, newaddr = 0x2359a8, rw = READ(), type = COLD_DATA
f2fs_submit_read_bio: dev = (253,7)/(253,7), rw = READ(), DATA,
  sector = 18533696, size = 4096
f2fs_get_victim: dev = (253,7), type = No TYPE,
  policy = (Foreground GC, LFS-mode, Greedy), victim = 4355, cost = 1,
  ofs_unit = 1, pre_victim_secno = 4355, prefree = 0, free = 234
f2fs_iget: dev = (253,7), ino = 6247, pino = 5845, i_mode = 0x81b0,
  i_size = 319488, i_nlink = 1, i_blocks = 624, i_advise = 0x2c

In that moment, we can observe:

[Before]
Try to move 5084219 blocks (BG: 384508)
  - data blocks : 4962373 (274483)
  - node blocks : 121846 (110025)
Skipped : atomic write 4534686 (10)

[After]
Try to move 5088973 blocks (BG: 384508)
  - data blocks : 4967127 (274483)
  - node blocks : 121846 (110025)
Skipped : atomic write 4539440 (10)

So, refactor atomic_write flow like this:
1. start_atomic_write
 - add inmem_list and set atomic_file

2. write()
 - register it in inmem_pages

3. commit_atomic_write
 - if no error, f2fs_drop_inmem_pages()
 - f2fs_commit_inmme_pages() failed
   : __revoked_inmem_pages() was done
 - f2fs_do_sync_file failed
   : abort_atomic_write later

4. abort_atomic_write
 - f2fs_drop_inmem_pages

5. f2fs_drop_inmem_pages
 - clear atomic_file
 - remove inmem_list

Based on this change, when GC fails to move block in atomic_file,
f2fs_drop_inmem_pages_all() can call f2fs_drop_inmem_pages().

Change-Id: I876038ae8ab980a9d7ab30f3a4416a9a7b9c9998
Reviewed-by: default avatarChao Yu <yuchao0@huawei.com>
Signed-off-by: default avatarJaegeuk Kim <jaegeuk@kernel.org>
Git-commit: 743b620cb0516f6b6cbc45b48df00fe6d14d00ba
Git-repo: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/


Signed-off-by: default avatarSayali Lokhande <sayalil@codeaurora.org>
parent c3fb549e

fs/f2fs/file.c

+10 −5
Original line number Diff line number Diff line
@@ -1741,6 +1741,8 @@ static int f2fs_ioc_getversion(struct file *filp, unsigned long arg) 
static int f2fs_ioc_start_atomic_write(struct file *filp)

{

	struct inode *inode = file_inode(filp);

	struct f2fs_inode_info *fi = F2FS_I(inode);

	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);

	int ret;



	if (!inode_owner_or_capable(inode))
@@ -1781,6 +1783,12 @@ static int f2fs_ioc_start_atomic_write(struct file *filp) 
		goto out;

	}



	spin_lock(&sbi->inode_lock[ATOMIC_FILE]);

	if (list_empty(&fi->inmem_ilist))

		list_add_tail(&fi->inmem_ilist, &sbi->inode_list[ATOMIC_FILE]);

	spin_unlock(&sbi->inode_lock[ATOMIC_FILE]);



	/* add inode in inmem_list first and set atomic_file */

	set_inode_flag(inode, FI_ATOMIC_FILE);

	clear_inode_flag(inode, FI_ATOMIC_REVOKE_REQUEST);

	up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
@@ -1822,11 +1830,8 @@ static int f2fs_ioc_commit_atomic_write(struct file *filp) 
			goto err_out;



		ret = f2fs_do_sync_file(filp, 0, LLONG_MAX, 0, true);

		if (!ret) {

			clear_inode_flag(inode, FI_ATOMIC_FILE);

			F2FS_I(inode)->i_gc_failures[GC_FAILURE_ATOMIC] = 0;

			stat_dec_atomic_write(inode);

		}

		if (!ret)

			f2fs_drop_inmem_pages(inode);

	} else {

		ret = f2fs_do_sync_file(filp, 0, LLONG_MAX, 1, false);

	}

fs/f2fs/segment.c

+8 −21
Original line number Diff line number Diff line
@@ -185,8 +185,6 @@ bool f2fs_need_SSR(struct f2fs_sb_info *sbi) 


void f2fs_register_inmem_page(struct inode *inode, struct page *page)

{

	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);

	struct f2fs_inode_info *fi = F2FS_I(inode);

	struct inmem_pages *new;



	f2fs_trace_pid(page);
@@ -200,15 +198,11 @@ void f2fs_register_inmem_page(struct inode *inode, struct page *page) 
	INIT_LIST_HEAD(&new->list);



	/* increase reference count with clean state */

	mutex_lock(&fi->inmem_lock);

	get_page(page);

	list_add_tail(&new->list, &fi->inmem_pages);

	spin_lock(&sbi->inode_lock[ATOMIC_FILE]);

	if (list_empty(&fi->inmem_ilist))

		list_add_tail(&fi->inmem_ilist, &sbi->inode_list[ATOMIC_FILE]);

	spin_unlock(&sbi->inode_lock[ATOMIC_FILE]);

	mutex_lock(&F2FS_I(inode)->inmem_lock);

	list_add_tail(&new->list, &F2FS_I(inode)->inmem_pages);

	inc_page_count(F2FS_I_SB(inode), F2FS_INMEM_PAGES);

	mutex_unlock(&fi->inmem_lock);

	mutex_unlock(&F2FS_I(inode)->inmem_lock);



	trace_f2fs_register_inmem_page(page, INMEM);

}
@@ -330,19 +324,17 @@ void f2fs_drop_inmem_pages(struct inode *inode) 
		mutex_lock(&fi->inmem_lock);

		__revoke_inmem_pages(inode, &fi->inmem_pages,

						true, false, true);



		if (list_empty(&fi->inmem_pages)) {

			spin_lock(&sbi->inode_lock[ATOMIC_FILE]);

			if (!list_empty(&fi->inmem_ilist))

				list_del_init(&fi->inmem_ilist);

			spin_unlock(&sbi->inode_lock[ATOMIC_FILE]);

		}

		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);

	spin_unlock(&sbi->inode_lock[ATOMIC_FILE]);

}



void f2fs_drop_inmem_page(struct inode *inode, struct page *page)
@@ -471,11 +463,6 @@ int f2fs_commit_inmem_pages(struct inode *inode) 


	mutex_lock(&fi->inmem_lock);

	err = __f2fs_commit_inmem_pages(inode);



	spin_lock(&sbi->inode_lock[ATOMIC_FILE]);

	if (!list_empty(&fi->inmem_ilist))

		list_del_init(&fi->inmem_ilist);

	spin_unlock(&sbi->inode_lock[ATOMIC_FILE]);

	mutex_unlock(&fi->inmem_lock);



	clear_inode_flag(inode, FI_ATOMIC_COMMIT);