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ovl: split ovl_want_write() into two helpers

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ovl_get_write_access() gets write access to upper mnt without taking
freeze protection on upper sb and ovl_start_write() only takes freeze
protection on upper sb.

These helpers will be used to breakup the large ovl_want_write() scope
during copy up into finer grained freeze protection scopes.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
This commit is contained in:
Amir Goldstein 2023-08-16 12:18:15 +03:00
parent c002728f60
commit d08d3b3c2c
2 changed files with 30 additions and 0 deletions
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4
fs/overlayfs/overlayfs.h
View File

@ -398,6 +398,10 @@ static inline bool ovl_open_flags_need_copy_up(int flags)
}
/* util.c */
int ovl_get_write_access(struct dentry *dentry);
void ovl_put_write_access(struct dentry *dentry);
void ovl_start_write(struct dentry *dentry);
void ovl_end_write(struct dentry *dentry);
int ovl_want_write(struct dentry *dentry);
void ovl_drop_write(struct dentry *dentry);
struct dentry *ovl_workdir(struct dentry *dentry);

26
fs/overlayfs/util.c
View File

@ -17,12 +17,38 @@
#include <linux/ratelimit.h>
#include "overlayfs.h"
/* Get write access to upper mnt - may fail if upper sb was remounted ro */
int ovl_get_write_access(struct dentry *dentry)
{
struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
return mnt_get_write_access(ovl_upper_mnt(ofs));
}
/* Get write access to upper sb - may block if upper sb is frozen */
void ovl_start_write(struct dentry *dentry)
{
struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
sb_start_write(ovl_upper_mnt(ofs)->mnt_sb);
}
int ovl_want_write(struct dentry *dentry)
{
struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
return mnt_want_write(ovl_upper_mnt(ofs));
}
void ovl_put_write_access(struct dentry *dentry)
{
struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
mnt_put_write_access(ovl_upper_mnt(ofs));
}
void ovl_end_write(struct dentry *dentry)
{
struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
sb_end_write(ovl_upper_mnt(ofs)->mnt_sb);
}
void ovl_drop_write(struct dentry *dentry)
{
struct ovl_fs *ofs = OVL_FS(dentry->d_sb);