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Diffstat (limited to 'fs/namei.c')
-rw-r--r--fs/namei.c144
1 files changed, 98 insertions, 46 deletions
diff --git a/fs/namei.c b/fs/namei.c
index 501000381..96ae55768 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -191,21 +191,35 @@ int permission(struct inode * inode,int mask)
* < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist
* > 0: (i_writecount) users are writing to the file.
*
- * WARNING: as soon as we will move get_write_access(), do_mmap() or
- * prepare_binfmt() out of the big lock we will need a spinlock protecting
- * the checks in all 3. For the time being it is not needed.
+ * Normally we operate on that counter with atomic_{inc,dec} and it's safe
+ * except for the cases where we don't hold i_writecount yet. Then we need to
+ * use {get,deny}_write_access() - these functions check the sign and refuse
+ * to do the change if sign is wrong. Exclusion between them is provided by
+ * spinlock (arbitration_lock) and I'll rip the second arsehole to the first
+ * who will try to move it in struct inode - just leave it here.
*/
+static spinlock_t arbitration_lock = SPIN_LOCK_UNLOCKED;
int get_write_access(struct inode * inode)
{
- if (atomic_read(&inode->i_writecount) < 0)
+ spin_lock(&arbitration_lock);
+ if (atomic_read(&inode->i_writecount) < 0) {
+ spin_unlock(&arbitration_lock);
return -ETXTBSY;
+ }
atomic_inc(&inode->i_writecount);
+ spin_unlock(&arbitration_lock);
return 0;
}
-
-void put_write_access(struct inode * inode)
+int deny_write_access(struct file * file)
{
- atomic_dec(&inode->i_writecount);
+ spin_lock(&arbitration_lock);
+ if (atomic_read(&file->f_dentry->d_inode->i_writecount) > 0) {
+ spin_unlock(&arbitration_lock);
+ return -ETXTBSY;
+ }
+ atomic_dec(&file->f_dentry->d_inode->i_writecount);
+ spin_unlock(&arbitration_lock);
+ return 0;
}
void path_release(struct nameidata *nd)
@@ -337,7 +351,34 @@ int follow_down(struct vfsmount **mnt, struct dentry **dentry)
{
return __follow_down(mnt,dentry);
}
-
+
+static inline void follow_dotdot(struct nameidata *nd)
+{
+ while(1) {
+ struct vfsmount *parent;
+ struct dentry *dentry;
+ if (nd->dentry == current->fs->root &&
+ nd->mnt == current->fs->rootmnt) {
+ break;
+ }
+ if (nd->dentry != nd->mnt->mnt_root) {
+ dentry = dget(nd->dentry->d_parent);
+ dput(nd->dentry);
+ nd->dentry = dentry;
+ break;
+ }
+ parent=nd->mnt->mnt_parent;
+ if (parent == nd->mnt) {
+ break;
+ }
+ mntget(parent);
+ dentry=dget(nd->mnt->mnt_mountpoint);
+ dput(nd->dentry);
+ nd->dentry = dentry;
+ mntput(nd->mnt);
+ nd->mnt = parent;
+ }
+}
/*
* Name resolution.
*
@@ -403,19 +444,7 @@ int path_walk(const char * name, struct nameidata *nd)
case 2:
if (this.name[1] != '.')
break;
- while (1) {
- if (nd->dentry == current->fs->root &&
- nd->mnt == current->fs->rootmnt)
- break;
- if (nd->dentry != nd->mnt->mnt_root) {
- dentry = dget(nd->dentry->d_parent);
- dput(nd->dentry);
- nd->dentry = dentry;
- break;
- }
- if (!__follow_up(&nd->mnt, &nd->dentry))
- break;
- }
+ follow_dotdot(nd);
inode = nd->dentry->d_inode;
/* fallthrough */
case 1:
@@ -483,19 +512,7 @@ last_component:
case 2:
if (this.name[1] != '.')
break;
- while (1) {
- if (nd->dentry == current->fs->root &&
- nd->mnt == current->fs->rootmnt)
- break;
- if (nd->dentry != nd->mnt->mnt_root) {
- dentry = dget(nd->dentry->d_parent);
- dput(nd->dentry);
- nd->dentry = dentry;
- break;
- }
- if (!__follow_up(&nd->mnt, &nd->dentry))
- break;
- }
+ follow_dotdot(nd);
inode = nd->dentry->d_inode;
/* fallthrough */
case 1:
@@ -771,8 +788,6 @@ static inline int may_delete(struct inode *dir,struct dentry *victim, int isdir)
int error;
if (!victim->d_inode || victim->d_parent->d_inode != dir)
return -ENOENT;
- if (IS_DEADDIR(dir))
- return -ENOENT;
error = permission(dir,MAY_WRITE | MAY_EXEC);
if (error)
return error;
@@ -786,8 +801,6 @@ static inline int may_delete(struct inode *dir,struct dentry *victim, int isdir)
return -ENOTDIR;
if (IS_ROOT(victim))
return -EBUSY;
- if (d_mountpoint(victim))
- return -EBUSY;
} else if (S_ISDIR(victim->d_inode->i_mode))
return -EISDIR;
return 0;
@@ -917,6 +930,22 @@ int open_namei(const char * pathname, int flag, int mode, struct nameidata *nd)
error = -EEXIST;
if (flag & O_EXCL)
goto exit_dput;
+ if (flag & O_NOFOLLOW) {
+ error = -ELOOP;
+ if (dentry->d_inode->i_op &&
+ dentry->d_inode->i_op->follow_link)
+ goto exit_dput;
+ if (d_mountpoint(dentry))
+ goto exit_dput;
+ goto got_it;
+ }
+ /* Check mountpoints - it may be a binding on file. */
+ while (d_mountpoint(dentry) &&
+ __follow_down(&nd->mnt, &dentry))
+ ;
+ error = -ENOENT;
+ if (!dentry->d_inode)
+ goto exit_dput;
if (dentry->d_inode->i_op &&
dentry->d_inode->i_op->follow_link) {
/*
@@ -930,6 +959,7 @@ int open_namei(const char * pathname, int flag, int mode, struct nameidata *nd)
return error;
dentry = nd->dentry;
} else {
+ got_it:
dput(nd->dentry);
nd->dentry = dentry;
}
@@ -962,6 +992,10 @@ int open_namei(const char * pathname, int flag, int mode, struct nameidata *nd)
if (S_ISDIR(inode->i_mode) && (flag & FMODE_WRITE))
goto exit;
+ error = -EOPNOTSUPP;
+ if (S_ISSOCK(inode->i_mode))
+ goto exit;
+
error = permission(inode,acc_mode);
if (error)
goto exit;
@@ -1213,9 +1247,15 @@ int vfs_rmdir(struct inode *dir, struct dentry *dentry)
double_down(&dir->i_zombie, &dentry->d_inode->i_zombie);
d_unhash(dentry);
- error = dir->i_op->rmdir(dir, dentry);
- if (!error)
- dentry->d_inode->i_flags |= S_DEAD;
+ if (IS_DEADDIR(dir))
+ error = -ENOENT;
+ else if (d_mountpoint(dentry))
+ error = -EBUSY;
+ else {
+ error = dir->i_op->rmdir(dir, dentry);
+ if (!error)
+ dentry->d_inode->i_flags |= S_DEAD;
+ }
double_up(&dir->i_zombie, &dentry->d_inode->i_zombie);
if (!error)
d_delete(dentry);
@@ -1275,9 +1315,13 @@ int vfs_unlink(struct inode *dir, struct dentry *dentry)
error = -EPERM;
if (dir->i_op && dir->i_op->unlink) {
DQUOT_INIT(dir);
- error = dir->i_op->unlink(dir, dentry);
- if (!error)
- d_delete(dentry);
+ if (d_mountpoint(dentry))
+ error = -EBUSY;
+ else {
+ error = dir->i_op->unlink(dir, dentry);
+ if (!error)
+ d_delete(dentry);
+ }
}
}
up(&dir->i_zombie);
@@ -1555,7 +1599,12 @@ int vfs_rename_dir(struct inode *old_dir, struct dentry *old_dentry,
} else
double_down(&old_dir->i_zombie,
&new_dir->i_zombie);
- error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
+ if (IS_DEADDIR(old_dir)||IS_DEADDIR(new_dir))
+ error = -ENOENT;
+ else if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry))
+ error = -EBUSY;
+ else
+ error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
if (target) {
if (!error)
target->i_flags |= S_DEAD;
@@ -1603,7 +1652,10 @@ int vfs_rename_other(struct inode *old_dir, struct dentry *old_dentry,
DQUOT_INIT(old_dir);
DQUOT_INIT(new_dir);
double_down(&old_dir->i_zombie, &new_dir->i_zombie);
- error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
+ if (d_mountpoint(old_dentry)||d_mountpoint(new_dentry))
+ error = -EBUSY;
+ else
+ error = old_dir->i_op->rename(old_dir, old_dentry, new_dir, new_dentry);
double_up(&old_dir->i_zombie, &new_dir->i_zombie);
if (error)
return error;
generated by cgit v1.2.3 (git 2.25.1) at 2024-09-19 23:56:34 +0000