kernel.git/fs/overlayfs/util.c, branch linux-6.5.y

ovl: store enum redirect_mode in config instead of a string

2023-06-19T11:02:01Z

Do all the logic to set the mode during mount options parsing and do not keep the option string around. Use a constant_table to translate from enum redirect mode to string in preperation for new mount api option parsing. The mount option "off" is translated to either "follow" or "nofollow", depending on the "redirect_always_follow" build/module config, so in effect, there are only three possible redirect modes. This results in a minor change to the string that is displayed in show_options() - when redirect_dir is enabled by default and the user mounts with the option "redirect_dir=off", instead of displaying the mode "redirect_dir=off" in show_options(), the displayed mode will be either "redirect_dir=follow" or "redirect_dir=nofollow", depending on the value of "redirect_always_follow" build/module config. The displayed mode reflects the effective mode, so mounting overlayfs again with the dispalyed redirect_dir option will result with the same effective and displayed mode. Signed-off-by: Amir Goldstein

ovl: implement lazy lookup of lowerdata in data-only layers

2023-06-19T11:01:14Z

Defer lookup of lowerdata in the data-only layers to first data access or before copy up. We perform lowerdata lookup before copy up even if copy up is metadata only copy up. We can further optimize this lookup later if needed. We do best effort lazy lookup of lowerdata for d_real_inode(), because this interface does not expect errors. The only current in-tree caller of d_real_inode() is trace_uprobe and this caller is likely going to be followed reading from the file, before placing uprobes on offset within the file, so lowerdata should be available when setting the uprobe. Tested-by: kernel test robot Reviewed-by: Alexander Larsson Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi

ovl: prepare for lazy lookup of lowerdata inode

2023-06-19T11:01:14Z

Make the code handle the case of numlower > 1 and missing lowerdata dentry gracefully. Missing lowerdata dentry is an indication for lazy lookup of lowerdata and in that case the lowerdata_redirect path is stored in ovl_inode. Following commits will defer lookup and perform the lazy lookup on access. Reviewed-by: Alexander Larsson Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi

ovl: prepare to store lowerdata redirect for lazy lowerdata lookup

2023-06-19T11:01:14Z

Prepare to allow ovl_lookup() to leave the last entry in a non-dir lowerstack empty to signify lazy lowerdata lookup. In this case, ovl_lookup() stores the redirect path from metacopy to lowerdata in ovl_inode, which is going to be used later to perform the lazy lowerdata lookup. Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi

ovl: deduplicate lowerdata and lowerstack[]

2023-06-19T11:01:13Z

The ovl_inode contains a copy of lowerdata in lowerstack[], so the lowerdata inode member can be removed. Use accessors ovl_lowerdata*() to get the lowerdata whereever the member was accessed directly. Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi

ovl: deduplicate lowerpath and lowerstack[]

2023-06-19T11:01:13Z

The ovl_inode contains a copy of lowerpath in lowerstack[0], so the lowerpath member can be removed. Use accessor ovl_lowerpath() to get the lowerpath whereever the member was accessed directly. Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi

ovl: move ovl_entry into ovl_inode

2023-06-19T11:01:13Z

The lower stacks of all the ovl inode aliases should be identical and there is redundant information in ovl_entry and ovl_inode. Move lowerstack into ovl_inode and keep only the OVL_E_FLAGS per overlay dentry. Following patches will deduplicate redundant ovl_inode fields. Note that for pure upper and negative dentries, OVL_E(dentry) may be NULL now, so it is imporatnt to use the ovl_numlower() accessor. Reviewed-by: Alexander Larsson Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi

ovl: factor out ovl_free_entry() and ovl_stack_*() helpers

2023-06-19T11:01:13Z

In preparation for moving lowerstack into ovl_inode. Note that in ovl_lookup() the temp stack dentry refs are now cloned into the final ovl_lowerstack instead of being transferred, so cleanup always needs to call ovl_stack_free(stack). Reviewed-by: Alexander Larsson Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi

ovl: use ovl_numlower() and ovl_lowerstack() accessors

2023-06-19T11:01:13Z

This helps fortify against dereferencing a NULL ovl_entry, before we move the ovl_entry reference into ovl_inode. Reviewed-by: Alexander Larsson Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi

ovl: use OVL_E() and OVL_E_FLAGS() accessors

2023-06-19T11:01:12Z

Instead of open coded instances, because we are about to split the two apart. Reviewed-by: Alexander Larsson Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi