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libmount: improve fs referencing in tables 

* Added member 'struct libmnt_table *tab' to libmnt_fs structure.
* Added 'mnt_fs_get_table()'.
* Removed overhead from 'mnt_table_{insert,move,remove}_fs().
* Added check to 'mnt_table_set_iter()' that entry is member of table.

[kzak@redhat.com: - add to libmount.sys
                  - add to docs
                  - cleanup commit message
                  - set fs->tab = NULL before mnt_unref_fs() in mnt_table_remove_fs()]

Signed-off-by: Tim Hildering <hilderingt@posteo.net>
Signed-off-by: Karel Zak <kzak@redhat.com>
This commit is contained in:
Tim Hildering 2019-03-04 19:15:08 +01:00 committed by Karel Zak
parent 64a87be1a4
commit 9d5eb4c464
6 changed files with 32 additions and 9 deletions
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1
libmount/docs/libmount-sections.txt
View File

@ -227,6 +227,7 @@ mnt_fs_get_source
mnt_fs_get_srcpath
mnt_fs_get_swaptype
mnt_fs_get_tag
mnt_fs_get_table
mnt_fs_get_target
mnt_fs_get_tid
mnt_fs_get_usedsize

17
libmount/src/fs.c
View File

@ -190,6 +190,7 @@ struct libmnt_fs *mnt_copy_fs(struct libmnt_fs *dest,
return NULL;
}
dest->tab = NULL;
dest->id = src->id;
dest->parent = src->parent;
dest->devno = src->devno;
@ -445,6 +446,22 @@ int mnt_fs_streq_srcpath(struct libmnt_fs *fs, const char *path)
return p && path && strcmp(p, path) == 0;
}
/**
* mnt_fs_get_table:
* @fs: table entry
* @tb: table that contains @fs
*
* Returns: 0 or negative number on error (if @fs or @tb is NULL).
*/
int mnt_fs_get_table(struct libmnt_fs *fs, struct libmnt_table **tb)
{
if (!fs || !tb)
return -EINVAL;
*tb = fs->tab;
return 0;
}
/**
* mnt_fs_streq_target:
* @fs: fs

1
libmount/src/libmount.h.in
View File

@ -439,6 +439,7 @@ extern int mnt_fs_set_userdata(struct libmnt_fs *fs, void *data);
extern const char *mnt_fs_get_source(struct libmnt_fs *fs);
extern int mnt_fs_set_source(struct libmnt_fs *fs, const char *source);
extern const char *mnt_fs_get_srcpath(struct libmnt_fs *fs);
extern int mnt_fs_get_table(struct libmnt_fs *fs, struct libmnt_table **tb);
extern int mnt_fs_get_tag(struct libmnt_fs *fs, const char **name,
const char **value);

1
libmount/src/libmount.sym
View File

@ -344,6 +344,7 @@ MOUNT_2.33 {
MOUNT_2.34 {
mnt_context_next_remount;
mnt_fs_get_table;
mnt_guess_system_root;
mnt_table_find_fs;
mnt_table_insert_fs;

1
libmount/src/mountP.h
View File

@ -170,6 +170,7 @@ struct libmnt_iter {
*/
struct libmnt_fs {
struct list_head ents;
struct libmnt_table *tab;
int refcount; /* reference counter */
int id; /* mountinfo[1]: ID */

20
libmount/src/tab.c
View File

@ -443,11 +443,12 @@ int mnt_table_add_fs(struct libmnt_table *tb, struct libmnt_fs *fs)
if (!tb || !fs)
return -EINVAL;
if (!list_empty(&fs->ents))
if (fs->tab)
return -EBUSY;
mnt_ref_fs(fs);
list_add_tail(&fs->ents, &tb->ents);
fs->tab = tb;
tb->nents++;
DBG(TAB, ul_debugobj(tb, "add entry: %s %s",
@ -466,6 +467,7 @@ static int __table_insert_fs(
else
list_add_tail(&fs->ents, head);
fs->tab = tb;
tb->nents++;
DBG(TAB, ul_debugobj(tb, "insert entry: %s %s",
@ -487,7 +489,6 @@ static int __table_insert_fs(
* This function inncrements reference to @fs. Don't forget to use
* mnt_unref_fs() after mnt_table_insert_fs() if you want to keep the @fs
* referenced by the table only.
*
* Returns: 0 on success or negative number in case of error.
*/
@ -497,10 +498,10 @@ int mnt_table_insert_fs(struct libmnt_table *tb, int before,
if (!tb || !fs)
return -EINVAL;
if (!list_empty(&fs->ents))
if (fs->tab)
return -EBUSY;
if (pos && mnt_table_find_fs(tb, pos) < 1)
if (pos && pos->tab != tb)
return -ENOENT;
mnt_ref_fs(fs);
@ -529,10 +530,7 @@ int mnt_table_move_fs(struct libmnt_table *src, struct libmnt_table *dst,
if (!src || !dst || !fs)
return -EINVAL;
if (mnt_table_find_fs(src, fs) < 1)
return -ENOENT;
if (pos && mnt_table_find_fs(dst, pos) < 1)
if (fs->tab != src || (pos && pos->tab != dst))
return -ENOENT;
/* remove from source */
@ -557,9 +555,10 @@ int mnt_table_move_fs(struct libmnt_table *src, struct libmnt_table *dst,
*/
int mnt_table_remove_fs(struct libmnt_table *tb, struct libmnt_fs *fs)
{
if (!tb || !fs || mnt_table_find_fs(tb, fs) < 1)
if (!tb || !fs || fs->tab != tb)
return -EINVAL;
fs->tab = NULL;
list_del_init(&fs->ents);
mnt_unref_fs(fs);
@ -913,6 +912,9 @@ int mnt_table_set_iter(struct libmnt_table *tb, struct libmnt_iter *itr, struct
if (!tb || !itr || !fs)
return -EINVAL;
if (fs->tab != tb)
return -ENOENT;
MNT_ITER_INIT(itr, &tb->ents);
itr->p = &fs->ents;