erofs: better erofs symlink stuffs

Fix as Christoph suggested [1] [2], "remove is_inode_fast_symlink
and just opencode it in the few places using it"

and
"Please just set the ops directly instead of obsfucating that in
a single caller, single line inline function.  And please set it
instead of the normal symlink iops in the same place where you
also set those."

[1] https://lore.kernel.org/r/20190830163910.GB29603@infradead.org/
[2] https://lore.kernel.org/r/20190829102426.GE20598@infradead.org/
Reported-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Link: https://lore.kernel.org/r/20190904020912.63925-13-gaoxiang25@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/erofs/inode.c b/fs/erofs/inode.c
index a42f5fc..770f325 100644 (file)
--- a/fs/erofs/inode.c
+++ b/fs/erofs/inode.c
@@ -127,50 +127,39 @@ bogusimode:
        return -EFSCORRUPTED;
 }
 
-/*
- * try_lock can be required since locking order is:
- *   file data(fs_inode)
- *        meta(bd_inode)
- * but the majority of the callers is "iget",
- * in that case we are pretty sure no deadlock since
- * no data operations exist. However I tend to
- * try_lock since it takes no much overhead and
- * will success immediately.
- */
-static int fill_inline_data(struct inode *inode, void *data,
-                           unsigned int m_pofs)
+static int erofs_fill_symlink(struct inode *inode, void *data,
+                             unsigned int m_pofs)
 {
        struct erofs_inode *vi = EROFS_I(inode);
        struct erofs_sb_info *sbi = EROFS_I_SB(inode);
+       char *lnk;
 
-       /* should be tail-packing data inline */
-       if (vi->datalayout != EROFS_INODE_FLAT_INLINE)
+       /* if it cannot be handled with fast symlink scheme */
+       if (vi->datalayout != EROFS_INODE_FLAT_INLINE ||
+           inode->i_size >= PAGE_SIZE) {
+               inode->i_op = &erofs_symlink_iops;
                return 0;
+       }
 
-       /* fast symlink */
-       if (S_ISLNK(inode->i_mode) && inode->i_size < PAGE_SIZE) {
-               char *lnk = erofs_kmalloc(sbi, inode->i_size + 1, GFP_KERNEL);
-
-               if (!lnk)
-                       return -ENOMEM;
-
-               m_pofs += vi->inode_isize + vi->xattr_isize;
+       lnk = erofs_kmalloc(sbi, inode->i_size + 1, GFP_KERNEL);
+       if (!lnk)
+               return -ENOMEM;
 
-               /* inline symlink data shouldn't cross page boundary as well */
-               if (m_pofs + inode->i_size > PAGE_SIZE) {
-                       kfree(lnk);
-                       errln("inline data cross block boundary @ nid %llu",
-                             vi->nid);
-                       DBG_BUGON(1);
-                       return -EFSCORRUPTED;
-               }
+       m_pofs += vi->inode_isize + vi->xattr_isize;
+       /* inline symlink data shouldn't cross page boundary as well */
+       if (m_pofs + inode->i_size > PAGE_SIZE) {
+               kfree(lnk);
+               errln("inline data cross block boundary @ nid %llu",
+                     vi->nid);
+               DBG_BUGON(1);
+               return -EFSCORRUPTED;
+       }
 
-               memcpy(lnk, data + m_pofs, inode->i_size);
-               lnk[inode->i_size] = '\0';
+       memcpy(lnk, data + m_pofs, inode->i_size);
+       lnk[inode->i_size] = '\0';
 
-               inode->i_link = lnk;
-               set_inode_fast_symlink(inode);
-       }
+       inode->i_link = lnk;
+       inode->i_op = &erofs_fast_symlink_iops;
        return 0;
 }
 
@@ -217,8 +206,9 @@ static int fill_inode(struct inode *inode, int isdir)
                        inode->i_fop = &erofs_dir_fops;
                        break;
                case S_IFLNK:
-                       /* by default, page_get_link is used for symlink */
-                       inode->i_op = &erofs_symlink_iops;
+                       err = erofs_fill_symlink(inode, data, ofs);
+                       if (err)
+                               goto out_unlock;
                        inode_nohighmem(inode);
                        break;
                case S_IFCHR:
@@ -237,11 +227,7 @@ static int fill_inode(struct inode *inode, int isdir)
                        err = z_erofs_fill_inode(inode);
                        goto out_unlock;
                }
-
                inode->i_mapping->a_ops = &erofs_raw_access_aops;
-
-               /* fill last page if inline data is available */
-               err = fill_inline_data(inode, data, ofs);
        }
 
 out_unlock:

diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index 10497ee..cc1ea98 100644 (file)
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -479,16 +479,6 @@ extern const struct inode_operations erofs_generic_iops;
 extern const struct inode_operations erofs_symlink_iops;
 extern const struct inode_operations erofs_fast_symlink_iops;
 
-static inline void set_inode_fast_symlink(struct inode *inode)
-{
-       inode->i_op = &erofs_fast_symlink_iops;
-}
-
-static inline bool is_inode_fast_symlink(struct inode *inode)
-{
-       return inode->i_op == &erofs_fast_symlink_iops;
-}
-
 struct inode *erofs_iget(struct super_block *sb, erofs_nid_t nid, bool dir);
 int erofs_getattr(const struct path *path, struct kstat *stat,
                  u32 request_mask, unsigned int query_flags);

diff --git a/fs/erofs/super.c b/fs/erofs/super.c
index 3986be5..b8b0e35 100644 (file)
--- a/fs/erofs/super.c
+++ b/fs/erofs/super.c
@@ -40,10 +40,9 @@ static void free_inode(struct inode *inode)
 {
        struct erofs_inode *vi = EROFS_I(inode);
 
-       /* be careful RCU symlink path (see ext4_inode_info->i_data)! */
-       if (is_inode_fast_symlink(inode))
+       /* be careful of RCU symlink path */
+       if (inode->i_op == &erofs_fast_symlink_iops)
                kfree(inode->i_link);
-
        kfree(vi->xattr_shared_xattrs);
 
        kmem_cache_free(erofs_inode_cachep, vi);