Because I found that it will still lead to out-of-free problem with out that check. I trace and find that it is possible that the committing date pages of the atomic file is bigger than the sbi->user_block_count - valid_user_blocks(sbi), so I add
this check.

On 2017/11/3 11:46, Jaegeuk Kim wrote:
On 10/30, Yunlong Song wrote:
f2fs_balance_fs only actives once in the commit_inmem_pages, but there
are more than one page to commit, so all the other pages will miss the
check. This will lead to out-of-free problem when commit a very large
file. However, we cannot do f2fs_balance_fs for each inmem page, since
this will break atomicity. As a result, we should collect prefree
segments if needed and stop atomic commit when there are not enough
available blocks to write atomic pages.

Signed-off-by: Yunlong Song <yunlong.s...@huawei.com>
---
  fs/f2fs/f2fs.h    |  1 +
  fs/f2fs/segment.c | 29 ++++++++++++++++++++++++++++-
  2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 13a96b8..04ce48f 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -610,6 +610,7 @@ struct f2fs_inode_info {
        struct list_head inmem_pages;   /* inmemory pages managed by f2fs */
        struct task_struct *inmem_task; /* store inmemory task */
        struct mutex inmem_lock;        /* lock for inmemory pages */
+       unsigned long inmem_blocks;     /* inmemory blocks */
        struct extent_tree *extent_tree;        /* cached extent_tree entry */
        struct rw_semaphore dio_rwsem[2];/* avoid racing between dio and gc */
        struct rw_semaphore i_mmap_sem;
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 46dfbca..813c110 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -210,6 +210,7 @@ void register_inmem_page(struct inode *inode, struct page 
*page)
                list_add_tail(&fi->inmem_ilist, &sbi->inode_list[ATOMIC_FILE]);
        spin_unlock(&sbi->inode_lock[ATOMIC_FILE]);
        inc_page_count(F2FS_I_SB(inode), F2FS_INMEM_PAGES);
+       fi->inmem_blocks++;
        mutex_unlock(&fi->inmem_lock);
trace_f2fs_register_inmem_page(page, INMEM);
@@ -221,6 +222,7 @@ static int __revoke_inmem_pages(struct inode *inode,
        struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
        struct inmem_pages *cur, *tmp;
        int err = 0;
+       struct f2fs_inode_info *fi = F2FS_I(inode);
list_for_each_entry_safe(cur, tmp, head, list) {
                struct page *page = cur->page;
@@ -263,6 +265,7 @@ static int __revoke_inmem_pages(struct inode *inode,
                list_del(&cur->list);
                kmem_cache_free(inmem_entry_slab, cur);
                dec_page_count(F2FS_I_SB(inode), F2FS_INMEM_PAGES);
+               fi->inmem_blocks--;
        }
        return err;
  }
@@ -302,6 +305,10 @@ void drop_inmem_pages(struct inode *inode)
        if (!list_empty(&fi->inmem_ilist))
                list_del_init(&fi->inmem_ilist);
        spin_unlock(&sbi->inode_lock[ATOMIC_FILE]);
+       if (fi->inmem_blocks) {
+               f2fs_bug_on(sbi, 1);
+               fi->inmem_blocks = 0;
+       }
        mutex_unlock(&fi->inmem_lock);
clear_inode_flag(inode, FI_ATOMIC_FILE);
@@ -326,6 +333,7 @@ void drop_inmem_page(struct inode *inode, struct page *page)
f2fs_bug_on(sbi, !cur || cur->page != page);
        list_del(&cur->list);
+       fi->inmem_blocks--;
        mutex_unlock(&fi->inmem_lock);
dec_page_count(sbi, F2FS_INMEM_PAGES);
@@ -410,11 +418,26 @@ int commit_inmem_pages(struct inode *inode)
INIT_LIST_HEAD(&revoke_list);
        f2fs_balance_fs(sbi, true);
+       if (prefree_segments(sbi)
+               && has_not_enough_free_secs(sbi, 0,
+               fi->inmem_blocks / BLKS_PER_SEC(sbi))) {
+               struct cp_control cpc;
+
+               cpc.reason = __get_cp_reason(sbi);
+               err = write_checkpoint(sbi, &cpc);
+               if (err)
+                       goto drop;
+       }
        f2fs_lock_op(sbi);
set_inode_flag(inode, FI_ATOMIC_COMMIT); mutex_lock(&fi->inmem_lock);
+       if ((sbi->user_block_count - valid_user_blocks(sbi)) <
What does this mean? We already allocated blocks successfully?

+               fi->inmem_blocks) {
+               err = -ENOSPC;
+               goto drop;
+       }
        err = __commit_inmem_pages(inode, &revoke_list);
        if (err) {
                int ret;
@@ -429,7 +452,7 @@ int commit_inmem_pages(struct inode *inode)
                ret = __revoke_inmem_pages(inode, &revoke_list, false, true);
                if (ret)
                        err = ret;
-
+drop:
                /* drop all uncommitted pages */
                __revoke_inmem_pages(inode, &fi->inmem_pages, true, false);
        }
@@ -437,6 +460,10 @@ int commit_inmem_pages(struct inode *inode)
        if (!list_empty(&fi->inmem_ilist))
                list_del_init(&fi->inmem_ilist);
        spin_unlock(&sbi->inode_lock[ATOMIC_FILE]);
+       if (fi->inmem_blocks) {
+               f2fs_bug_on(sbi, 1);
+               fi->inmem_blocks = 0;
+       }
        mutex_unlock(&fi->inmem_lock);
clear_inode_flag(inode, FI_ATOMIC_COMMIT);
--
1.8.5.2
.


--
Thanks,
Yunlong Song



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