[PATCH 07/53] VFS: Add LOOKUP_SHARED flag.
NeilBrown <[email protected]>
| Newsgroups | gmane.linux.uml.devel,gmane.linux.file-systems,gmane.linux.nfs,gmane.linux.file-systems.union,gmane.linux.kernel.mm,gmane.linux.kernel.cifs,gmane.comp.file-systems.ext4,gmane.linux.kernel,gmane.comp.file-systems.ceph.devel,gmane.comp.file-systems.ecryptfs.general,gmane.linux.kernel.efi |
|---|---|
| Message-ID | <[email protected]> |
From: NeilBrown <[email protected]> Some ->lookup handlers will need to drop and retake the parent lock, so they can safely use d_alloc_parallel(). ->lookup can be called with the parent lock either exclusive or shared. A new flag, LOOKUP_SHARED, tells ->lookup how the parent is locked. This is rather ugly, but will be gone by the end of the series when ->lookup is *always* called with a shared lock on the parent. Signed-off-by: NeilBrown <[email protected]> --- fs/namei.c | 7 ++++--- include/linux/namei.h | 3 ++- 2 files changed, 6 insertions(+), 4 deletions(-) diff --git a/fs/namei.c b/fs/namei.c index d31c3db7eb5e..eed388ee8a30 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -1928,7 +1928,7 @@ static noinline struct dentry *lookup_slow(const struct qstr *name, struct inode *inode = dir->d_inode; struct dentry *res; inode_lock_shared(inode); - res = __lookup_slow(name, dir, flags); + res = __lookup_slow(name, dir, flags | LOOKUP_SHARED); inode_unlock_shared(inode); return res; } @@ -1942,7 +1942,7 @@ static struct dentry *lookup_slow_killable(const struct qstr *name, if (inode_lock_shared_killable(inode)) return ERR_PTR(-EINTR); - res = __lookup_slow(name, dir, flags); + res = __lookup_slow(name, dir, flags | LOOKUP_SHARED); inode_unlock_shared(inode); return res; } @@ -4407,6 +4407,7 @@ static struct dentry *lookup_open(struct nameidata *nd, struct file *file, struct dentry *dentry; int error, create_error = 0; umode_t mode = op->mode; + unsigned int shared_flag = (op->open_flag & O_CREAT) ? 0 : LOOKUP_SHARED; if (unlikely(IS_DEADDIR(dir_inode))) return ERR_PTR(-ENOENT); @@ -4474,7 +4475,7 @@ static struct dentry *lookup_open(struct nameidata *nd, struct file *file, if (d_in_lookup(dentry)) { struct dentry *res = dir_inode->i_op->lookup(dir_inode, dentry, - nd->flags); + nd->flags | shared_flag); d_lookup_done(dentry); if (unlikely(res)) { if (IS_ERR(res)) { diff --git a/include/linux/namei.h b/include/linux/namei.h index 2ad6dd9987b9..b3346a513d8f 100644 --- a/include/linux/namei.h +++ b/include/linux/namei.h @@ -37,8 +37,9 @@ enum {LAST_NORM, LAST_ROOT, LAST_DOT, LAST_DOTDOT}; #define LOOKUP_CREATE BIT(17) /* ... in object creation */ #define LOOKUP_EXCL BIT(18) /* ... in target must not exist */ #define LOOKUP_RENAME_TARGET BIT(19) /* ... in destination of rename() */ +#define LOOKUP_SHARED BIT(20) /* Parent lock is held shared */ -/* 4 spare bits for intent */ +/* 3 spare bits for intent */ /* Scoping flags for lookup. */ #define LOOKUP_NO_SYMLINKS BIT(24) /* No symlink crossing. */ -- 2.50.0.107.gf914562f5916.dirty