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 commited 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
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().

Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

2 files changed, 18 insertions, 26 deletions

diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 10927a0b8df3..fab6e4cf8f06 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -1829,6 +1829,8 @@ 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))
@@ -1871,6 +1873,12 @@ 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]);
@@ -1912,11 +1920,8 @@ 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);
         }
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 18584d4c078a..204524943bc6 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -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);