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| author | Amir Goldstein <amir73il@gmail.com> | 2023-04-27 13:39:09 +0300 |
|---|---|---|
| committer | Amir Goldstein <amir73il@gmail.com> | 2023-06-19 14:01:14 +0300 |
| commit | 42dd69ae1af42cf72d167e63a039b8c63653eb7f (patch) | |
| tree | da3f8b549fc66bfbf52747724869f7d9a2da28bb /fs/overlayfs/file.c | |
| parent | 416656447864ef0fc2430525499f52a4a370a0ab (diff) | |
| download | linux-42dd69ae1af42cf72d167e63a039b8c63653eb7f.tar.xz | |
ovl: implement lazy lookup of lowerdata in data-only layers
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 <oliver.sang@intel.com>
Reviewed-by: Alexander Larsson <alexl@redhat.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Diffstat (limited to 'fs/overlayfs/file.c')
| -rw-r--r-- | fs/overlayfs/file.c | 18 |
1 files changed, 14 insertions, 4 deletions
diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c index 951683a66ff6..39737c2aaa84 100644 --- a/fs/overlayfs/file.c +++ b/fs/overlayfs/file.c @@ -107,15 +107,21 @@ static int ovl_real_fdget_meta(const struct file *file, struct fd *real, { struct dentry *dentry = file_dentry(file); struct path realpath; + int err; real->flags = 0; real->file = file->private_data; - if (allow_meta) + if (allow_meta) { ovl_path_real(dentry, &realpath); - else + } else { + /* lazy lookup of lowerdata */ + err = ovl_maybe_lookup_lowerdata(dentry); + if (err) + return err; + ovl_path_realdata(dentry, &realpath); - /* TODO: lazy lookup of lowerdata */ + } if (!realpath.dentry) return -EIO; @@ -153,6 +159,11 @@ static int ovl_open(struct inode *inode, struct file *file) struct path realpath; int err; + /* lazy lookup of lowerdata */ + err = ovl_maybe_lookup_lowerdata(dentry); + if (err) + return err; + err = ovl_maybe_copy_up(dentry, file->f_flags); if (err) return err; @@ -161,7 +172,6 @@ static int ovl_open(struct inode *inode, struct file *file) file->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC); ovl_path_realdata(dentry, &realpath); - /* TODO: lazy lookup of lowerdata */ if (!realpath.dentry) return -EIO; |