Commit 3d268c9b136f51385f9d041f3f2424501b257388
1 parent
1be47b387a
Exists in
ti-lsk-linux-4.1.y
and in
10 other branches
overlayfs: don't hold ->i_mutex over opening the real directory
just use it to serialize the assignment Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Showing 1 changed file with 13 additions and 6 deletions Side-by-side Diff
fs/overlayfs/readdir.c
| ... | ... | @@ -458,20 +458,27 @@ |
| 458 | 458 | if (!od->is_upper && ovl_path_type(dentry) == OVL_PATH_MERGE) { |
| 459 | 459 | struct inode *inode = file_inode(file); |
| 460 | 460 | |
| 461 | - mutex_lock(&inode->i_mutex); | |
| 462 | 461 | realfile = od->upperfile; |
| 463 | 462 | if (!realfile) { |
| 464 | 463 | struct path upperpath; |
| 465 | 464 | |
| 466 | 465 | ovl_path_upper(dentry, &upperpath); |
| 467 | 466 | realfile = ovl_path_open(&upperpath, O_RDONLY); |
| 468 | - if (IS_ERR(realfile)) { | |
| 469 | - mutex_unlock(&inode->i_mutex); | |
| 470 | - return PTR_ERR(realfile); | |
| 467 | + mutex_lock(&inode->i_mutex); | |
| 468 | + if (!od->upperfile) { | |
| 469 | + if (IS_ERR(realfile)) { | |
| 470 | + mutex_unlock(&inode->i_mutex); | |
| 471 | + return PTR_ERR(realfile); | |
| 472 | + } | |
| 473 | + od->upperfile = realfile; | |
| 474 | + } else { | |
| 475 | + /* somebody has beaten us to it */ | |
| 476 | + if (!IS_ERR(realfile)) | |
| 477 | + fput(realfile); | |
| 478 | + realfile = od->upperfile; | |
| 471 | 479 | } |
| 472 | - od->upperfile = realfile; | |
| 480 | + mutex_unlock(&inode->i_mutex); | |
| 473 | 481 | } |
| 474 | - mutex_unlock(&inode->i_mutex); | |
| 475 | 482 | } |
| 476 | 483 | |
| 477 | 484 | return vfs_fsync_range(realfile, start, end, datasync); |