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Merge tag 'ovl-update-4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs

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Pull overlayfs updates from Miklos Szeredi:
 "This contains two new features:

   - Stack file operations: this allows removal of several hacks from
     the VFS, proper interaction of read-only open files with copy-up,
     possibility to implement fs modifying ioctls properly, and others.

   - Metadata only copy-up: when file is on lower layer and only
     metadata is modified (except size) then only copy up the metadata
     and continue to use the data from the lower file"

* tag 'ovl-update-4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs: (66 commits)
  ovl: Enable metadata only feature
  ovl: Do not do metacopy only for ioctl modifying file attr
  ovl: Do not do metadata only copy-up for truncate operation
  ovl: add helper to force data copy-up
  ovl: Check redirect on index as well
  ovl: Set redirect on upper inode when it is linked
  ovl: Set redirect on metacopy files upon rename
  ovl: Do not set dentry type ORIGIN for broken hardlinks
  ovl: Add an inode flag OVL_CONST_INO
  ovl: Treat metacopy dentries as type OVL_PATH_MERGE
  ovl: Check redirects for metacopy files
  ovl: Move some dir related ovl_lookup_single() code in else block
  ovl: Do not expose metacopy only dentry from d_real()
  ovl: Open file with data except for the case of fsync
  ovl: Add helper ovl_inode_realdata()
  ovl: Store lower data inode in ovl_inode
  ovl: Fix ovl_getattr() to get number of blocks from lower
  ovl: Add helper ovl_dentry_lowerdata() to get lower data dentry
  ovl: Copy up meta inode data from lowest data inode
  ovl: Modify ovl_lookup() and friends to lookup metacopy dentry
  ...
This commit is contained in:
Linus Torvalds
2018-08-21 18:19:09 -07:00
parent c22fc16d17 989974c804
commit d9a185f8b4
33 changed files with 1624 additions and 600 deletions
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69
fs/namespace.c
View File

@@ -430,75 +430,21 @@ int __mnt_want_write_file(struct file *file)
return mnt_clone_write(file->f_path.mnt);
}
/**
* mnt_want_write_file_path - get write access to a file's mount
* @file: the file who's mount on which to take a write
*
* This is like mnt_want_write, but it takes a file and can
* do some optimisations if the file is open for write already
*
* Called by the vfs for cases when we have an open file at hand, but will do an
* inode operation on it (important distinction for files opened on overlayfs,
* since the file operations will come from the real underlying file, while
* inode operations come from the overlay).
*/
int mnt_want_write_file_path(struct file *file)
{
int ret;
sb_start_write(file->f_path.mnt->mnt_sb);
ret = __mnt_want_write_file(file);
if (ret)
sb_end_write(file->f_path.mnt->mnt_sb);
return ret;
}
static inline int may_write_real(struct file *file)
{
struct dentry *dentry = file->f_path.dentry;
struct dentry *upperdentry;
/* Writable file? */
if (file->f_mode & FMODE_WRITER)
return 0;
/* Not overlayfs? */
if (likely(!(dentry->d_flags & DCACHE_OP_REAL)))
return 0;
/* File refers to upper, writable layer? */
upperdentry = d_real(dentry, NULL, 0, D_REAL_UPPER);
if (upperdentry &&
(file_inode(file) == d_inode(upperdentry) ||
file_inode(file) == d_inode(dentry)))
return 0;
/* Lower layer: can't write to real file, sorry... */
return -EPERM;
}
/**
* mnt_want_write_file - get write access to a file's mount
* @file: the file who's mount on which to take a write
*
* This is like mnt_want_write, but it takes a file and can
* do some optimisations if the file is open for write already
*
* Mostly called by filesystems from their ioctl operation before performing
* modification. On overlayfs this needs to check if the file is on a read-only
* lower layer and deny access in that case.
*/
int mnt_want_write_file(struct file *file)
{
int ret;
ret = may_write_real(file);
if (!ret) {
sb_start_write(file_inode(file)->i_sb);
ret = __mnt_want_write_file(file);
if (ret)
sb_end_write(file_inode(file)->i_sb);
}
sb_start_write(file_inode(file)->i_sb);
ret = __mnt_want_write_file(file);
if (ret)
sb_end_write(file_inode(file)->i_sb);
return ret;
}
EXPORT_SYMBOL_GPL(mnt_want_write_file);
@@ -538,14 +484,9 @@ void __mnt_drop_write_file(struct file *file)
__mnt_drop_write(file->f_path.mnt);
}
void mnt_drop_write_file_path(struct file *file)
{
mnt_drop_write(file->f_path.mnt);
}
void mnt_drop_write_file(struct file *file)
{
__mnt_drop_write(file->f_path.mnt);
__mnt_drop_write_file(file);
sb_end_write(file_inode(file)->i_sb);
}
EXPORT_SYMBOL(mnt_drop_write_file);