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ovl: concurrent copy up of regular files

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Now that copy up of regular file is done using O_TMPFILE,
we don't need to hold rename_lock throughout copy up.

Use the copy up waitqueue to synchronize concurrent copy up
of the same file. Different regular files can be copied up
concurrently.

The upper dir inode_lock is taken instead of rename_lock,
because it is needed for lookup and later for linking the
temp file, but it is released while copying up data.

Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This commit is contained in:
Amir Goldstein 2017-01-17 06:34:57 +02:00 committed by Miklos Szeredi
parent 39d3d60a54
commit 01ad3eb8a0
1 changed files with 31 additions and 4 deletions
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35
fs/overlayfs/copy_up.c
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@ -291,7 +291,16 @@ static int ovl_copy_up_locked(struct dentry *workdir, struct dentry *upperdir,
BUG_ON(upperpath.dentry != NULL);
upperpath.dentry = temp;
err = ovl_copy_up_data(lowerpath, &upperpath, stat->size);
if (tmpfile) {
inode_unlock(udir);
err = ovl_copy_up_data(lowerpath, &upperpath,
stat->size);
inode_lock_nested(udir, I_MUTEX_PARENT);
} else {
err = ovl_copy_up_data(lowerpath, &upperpath,
stat->size);
}
if (err)
goto out_cleanup;
}
@ -353,8 +362,6 @@ static int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
struct dentry *upperdir;
const char *link = NULL;
struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
/* Should we copyup with O_TMPFILE or with workdir? */
bool tmpfile = S_ISREG(stat->mode) && ofs->tmpfile;
if (WARN_ON(!workdir))
return -EROFS;
@ -374,6 +381,25 @@ static int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
return PTR_ERR(link);
}
/* Should we copyup with O_TMPFILE or with workdir? */
if (S_ISREG(stat->mode) && ofs->tmpfile) {
err = ovl_copy_up_start(dentry);
/* err < 0: interrupted, err > 0: raced with another copy-up */
if (unlikely(err)) {
pr_debug("ovl_copy_up_start(%pd2) = %i\n", dentry, err);
if (err > 0)
err = 0;
goto out_done;
}
inode_lock_nested(upperdir->d_inode, I_MUTEX_PARENT);
err = ovl_copy_up_locked(workdir, upperdir, dentry, lowerpath,
stat, link, &pstat, true);
inode_unlock(upperdir->d_inode);
ovl_copy_up_end(dentry);
goto out_done;
}
err = -EIO;
if (lock_rename(workdir, upperdir) != NULL) {
pr_err("overlayfs: failed to lock workdir+upperdir\n");
@ -386,9 +412,10 @@ static int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
}
err = ovl_copy_up_locked(workdir, upperdir, dentry, lowerpath,
stat, link, &pstat, tmpfile);
stat, link, &pstat, false);
out_unlock:
unlock_rename(workdir, upperdir);
out_done:
do_delayed_call(&done);
return err;