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| author | Al Viro <viro@zeniv.linux.org.uk> | 2015-05-04 17:47:11 -0400 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2015-05-10 22:20:12 -0400 |
| commit | 4693a547cded42807ec468947b4d5287f2cb6aa9 (patch) | |
| tree | cd945ed0efeddbc285f36492a97b459a7bbe32f0 /fs/namei.c | |
| parent | 8620c238edbf373aafcc4ee129e76c8e794c5214 (diff) | |
| download | lwn-4693a547cded42807ec468947b4d5287f2cb6aa9.tar.gz lwn-4693a547cded42807ec468947b4d5287f2cb6aa9.zip | |
namei: new calling conventions for walk_component()
instead of a single flag (!= 0 => we want to follow symlinks) pass
two bits - WALK_GET (want to follow symlinks) and WALK_PUT (put_link()
once we are done looking at the name). The latter matters only for
success exits - on failure the caller will discard everything anyway.
Suggestions for better variant are welcome; what this thing aims for
is making sure that pending put_link() is done *before* walk_component()
decides to pick a symlink up, rather than between picking it up and
acting upon it. See the next commit for payoff.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/namei.c')
| -rw-r--r-- | fs/namei.c | 30 |
1 files changed, 20 insertions, 10 deletions
diff --git a/fs/namei.c b/fs/namei.c index 19e5c8a27ea4..1c9af92518a1 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -1577,7 +1577,9 @@ static inline int should_follow_link(struct dentry *dentry, int follow) return unlikely(d_is_symlink(dentry)) ? follow : 0; } -static int walk_component(struct nameidata *nd, int follow) +enum {WALK_GET = 1, WALK_PUT = 2}; + +static int walk_component(struct nameidata *nd, int flags) { struct path path; struct inode *inode; @@ -1587,8 +1589,12 @@ static int walk_component(struct nameidata *nd, int follow) * to be able to know about the current root directory and * parent relationships. */ - if (unlikely(nd->last_type != LAST_NORM)) - return handle_dots(nd, nd->last_type); + if (unlikely(nd->last_type != LAST_NORM)) { + err = handle_dots(nd, nd->last_type); + if (flags & WALK_PUT) + put_link(nd); + return err; + } err = lookup_fast(nd, &path, &inode); if (unlikely(err)) { if (err < 0) @@ -1604,7 +1610,9 @@ static int walk_component(struct nameidata *nd, int follow) goto out_path_put; } - if (should_follow_link(path.dentry, follow)) { + if (flags & WALK_PUT) + put_link(nd); + if (should_follow_link(path.dentry, flags & WALK_GET)) { if (nd->flags & LOOKUP_RCU) { if (unlikely(nd->path.mnt != path.mnt || unlazy_walk(nd, path.dentry))) { @@ -1816,10 +1824,9 @@ OK: if (!name) return 0; /* last component of nested symlink */ - err = walk_component(nd, LOOKUP_FOLLOW); - put_link(nd); + err = walk_component(nd, WALK_GET | WALK_PUT); } else { - err = walk_component(nd, LOOKUP_FOLLOW); + err = walk_component(nd, WALK_GET); } if (err < 0) break; @@ -2017,9 +2024,12 @@ static inline int lookup_last(struct nameidata *nd) nd->flags |= LOOKUP_FOLLOW | LOOKUP_DIRECTORY; nd->flags &= ~LOOKUP_PARENT; - err = walk_component(nd, nd->flags & LOOKUP_FOLLOW); - if (nd->depth) - put_link(nd); + err = walk_component(nd, + nd->flags & LOOKUP_FOLLOW + ? nd->depth + ? WALK_PUT | WALK_GET + : WALK_GET + : 0); if (err < 0) terminate_walk(nd); return err; |