f2fs: avoid f2fs_lock_op for IPU writes

Currently, if we do get_node_of_data before f2fs_lock_op, there may be dead lock
as follows, where process A would be in infinite loop, and B will NOT be awaked.

Process A(cp):            Process B:
f2fs_lock_all(sbi)
                        get_dnode_of_data <---- lock dn.node_page
flush_nodes             f2fs_lock_op

So, this patch adds f2fs_trylock_op to avoid f2fs_lock_op done by IPU.

Signed-off-by: Hou Pengyang <houpengyang@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 4ca0899621a0cb2fecac0e94ceb5ed3632f208e3..779a306858a22a414139c7247a17d76b02190ba0 100644 (file)
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1383,12 +1383,12 @@ int do_write_data_page(struct f2fs_io_info *fio)
 
                if (valid_ipu_blkaddr(fio)) {
                        ipu_force = true;
-                       fio->need_lock = false;
+                       fio->need_lock = LOCK_DONE;
                        goto got_it;
                }
        }
 
-       if (fio->need_lock)
+       if (fio->need_lock == LOCK_REQ)
                f2fs_lock_op(fio->sbi);
 
        err = get_dnode_of_data(&dn, page->index, LOOKUP_NODE);
@@ -1403,19 +1403,18 @@ int do_write_data_page(struct f2fs_io_info *fio)
                goto out_writepage;
        }
 got_it:
-       err = encrypt_one_page(fio);
-       if (err)
-               goto out_writepage;
-
-       set_page_writeback(page);
-
        /*
         * If current allocation needs SSR,
         * it had better in-place writes for updated data.
         */
        if (ipu_force || (valid_ipu_blkaddr(fio) && need_inplace_update(fio))) {
+               err = encrypt_one_page(fio);
+               if (err)
+                       goto out_writepage;
+
+               set_page_writeback(page);
                f2fs_put_dnode(&dn);
-               if (fio->need_lock)
+               if (fio->need_lock == LOCK_REQ)
                        f2fs_unlock_op(fio->sbi);
                err = rewrite_data_page(fio);
                trace_f2fs_do_write_data_page(fio->page, IPU);
@@ -1423,6 +1422,20 @@ got_it:
                return err;
        }
 
+       if (fio->need_lock == LOCK_RETRY) {
+               if (!f2fs_trylock_op(fio->sbi)) {
+                       err = -EAGAIN;
+                       goto out_writepage;
+               }
+               fio->need_lock = LOCK_REQ;
+       }
+
+       err = encrypt_one_page(fio);
+       if (err)
+               goto out_writepage;
+
+       set_page_writeback(page);
+
        /* LFS mode write path */
        write_data_page(&dn, fio);
        trace_f2fs_do_write_data_page(page, OPU);
@@ -1432,7 +1445,7 @@ got_it:
 out_writepage:
        f2fs_put_dnode(&dn);
 out:
-       if (fio->need_lock)
+       if (fio->need_lock == LOCK_REQ)
                f2fs_unlock_op(fio->sbi);
        return err;
 }
@@ -1458,7 +1471,7 @@ static int __write_data_page(struct page *page, bool *submitted,
                .page = page,
                .encrypted_page = NULL,
                .submitted = false,
-               .need_lock = true,
+               .need_lock = LOCK_RETRY,
        };
 
        trace_f2fs_writepage(page, DATA);
@@ -1494,7 +1507,7 @@ write:
 
        /* Dentry blocks are controlled by checkpoint */
        if (S_ISDIR(inode->i_mode)) {
-               fio.need_lock = false;
+               fio.need_lock = LOCK_DONE;
                err = do_write_data_page(&fio);
                goto done;
        }
@@ -1513,8 +1526,13 @@ write:
                        goto out;
        }
 
-       if (err == -EAGAIN)
+       if (err == -EAGAIN) {
                err = do_write_data_page(&fio);
+               if (err == -EAGAIN) {
+                       fio.need_lock = LOCK_REQ;
+                       err = do_write_data_page(&fio);
+               }
+       }
        if (F2FS_I(inode)->last_disk_size < psize)
                F2FS_I(inode)->last_disk_size = psize;
 

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index c6643783adfff690ed296a4a5e58929e60bbbd7a..f61e095947c81450ea9773d3ccbe86b23311f524 100644 (file)
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -799,6 +799,12 @@ enum temp_type {
        NR_TEMP_TYPE,
 };
 
+enum need_lock_type {
+       LOCK_REQ = 0,
+       LOCK_DONE,
+       LOCK_RETRY,
+};
+
 struct f2fs_io_info {
        struct f2fs_sb_info *sbi;       /* f2fs_sb_info pointer */
        enum page_type type;    /* contains DATA/NODE/META/META_FLUSH */
@@ -810,7 +816,7 @@ struct f2fs_io_info {
        struct page *page;      /* page to be written */
        struct page *encrypted_page;    /* encrypted page */
        bool submitted;         /* indicate IO submission */
-       bool need_lock;         /* indicate we need to lock cp_rwsem */
+       int need_lock;          /* indicate we need to lock cp_rwsem */
 };
 
 #define is_read_io(rw) ((rw) == READ)
@@ -1279,6 +1285,11 @@ static inline void f2fs_lock_op(struct f2fs_sb_info *sbi)
        down_read(&sbi->cp_rwsem);
 }
 
+static inline int f2fs_trylock_op(struct f2fs_sb_info *sbi)
+{
+       return down_read_trylock(&sbi->cp_rwsem);
+}
+
 static inline void f2fs_unlock_op(struct f2fs_sb_info *sbi)
 {
        up_read(&sbi->cp_rwsem);

diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index e2b13558a915cbed7fcc99490ed33dd974406a5b..14c71ac760621ef9928b3d2573c8593fbf2ee259 100644 (file)
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -719,7 +719,7 @@ static void move_data_page(struct inode *inode, block_t bidx, int gc_type,
                        .old_blkaddr = NULL_ADDR,
                        .page = page,
                        .encrypted_page = NULL,
-                       .need_lock = true,
+                       .need_lock = LOCK_REQ,
                };
                bool is_dirty = PageDirty(page);
                int err;

diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index fcada9d03817b8a47ce69a38cd43a8cf0ebea408..3bc36769ec9f7b73320acbfeb76b7e4251bf36e6 100644 (file)
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -312,7 +312,7 @@ static int __commit_inmem_pages(struct inode *inode,
                        fio.page = page;
                        fio.old_blkaddr = NULL_ADDR;
                        fio.encrypted_page = NULL;
-                       fio.need_lock = false,
+                       fio.need_lock = LOCK_DONE;
                        err = do_write_data_page(&fio);
                        if (err) {
                                unlock_page(page);