353 lines
9.8 KiB
Diff
353 lines
9.8 KiB
Diff
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From 317add745924e5a4ad186691eede19d5a7c5eb10 Mon Sep 17 00:00:00 2001
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From: Karel Zak <kzak@redhat.com>
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Date: Fri, 19 Jan 2024 12:58:50 +0100
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Subject: libmount: cleanup locking in table update code
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* use reference counting for libmnt_lock
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* remove lock use from mnt_update_already_done(), it's read-only
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operation and utab update is atomic (based on rename(2))
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* keep the lock instance mandatory for all low-level update_*
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functions. The lock is always initialized, so all the 'if(lc)'
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are unnecessary.
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Addresses: https://issues.redhat.com/browse/RHEL-14612
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Upstream: http://github.com/util-linux/util-linux/commit/b94b5929a63df9786020e0329e94d2f35f3993ae
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Signed-off-by: Karel Zak <kzak@redhat.com>
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---
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libmount/src/context.c | 2 +-
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libmount/src/mountP.h | 3 +-
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libmount/src/tab_update.c | 118 +++++++++++++++++---------------------
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3 files changed, 56 insertions(+), 67 deletions(-)
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diff --git a/libmount/src/context.c b/libmount/src/context.c
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index ca7ea70d0..06ac50dc2 100644
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--- a/libmount/src/context.c
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+++ b/libmount/src/context.c
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@@ -2290,7 +2290,7 @@ int mnt_context_update_tabs(struct libmnt_context *cxt)
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&& mnt_context_get_helper_status(cxt) == 0
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&& mnt_context_utab_writable(cxt)) {
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- if (mnt_update_already_done(cxt->update, cxt->lock)) {
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+ if (mnt_update_already_done(cxt->update)) {
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DBG(CXT, ul_debugobj(cxt, "don't update: error evaluate or already updated"));
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goto emit;
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}
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diff --git a/libmount/src/mountP.h b/libmount/src/mountP.h
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index 99b913c99..eddc82bde 100644
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--- a/libmount/src/mountP.h
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+++ b/libmount/src/mountP.h
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@@ -477,8 +477,7 @@ extern int mnt_context_deferred_delete_veritydev(struct libmnt_context *cxt);
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extern int mnt_update_set_filename(struct libmnt_update *upd,
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const char *filename, int userspace_only);
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extern int mnt_update_emit_event(struct libmnt_update *upd);
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-extern int mnt_update_already_done(struct libmnt_update *upd,
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- struct libmnt_lock *lc);
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+extern int mnt_update_already_done(struct libmnt_update *upd);
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#if __linux__
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/* btrfs.c */
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diff --git a/libmount/src/tab_update.c b/libmount/src/tab_update.c
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index 70013a205..25a734e9d 100644
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--- a/libmount/src/tab_update.c
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+++ b/libmount/src/tab_update.c
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@@ -42,6 +42,7 @@ struct libmnt_update {
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missing_options : 1;
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struct libmnt_table *mountinfo;
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+ struct libmnt_lock *lock;
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};
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static int set_fs_root(struct libmnt_update *upd, struct libmnt_fs *fs, unsigned long mountflags);
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@@ -77,6 +78,7 @@ void mnt_free_update(struct libmnt_update *upd)
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DBG(UPDATE, ul_debugobj(upd, "free"));
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+ mnt_unref_lock(upd->lock);
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mnt_unref_fs(upd->fs);
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mnt_unref_table(upd->mountinfo);
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free(upd->target);
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@@ -691,18 +693,18 @@ static int add_file_entry(struct libmnt_table *tb, struct libmnt_update *upd)
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return update_table(upd, tb);
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}
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-static int update_add_entry(struct libmnt_update *upd, struct libmnt_lock *lc)
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+static int update_add_entry(struct libmnt_update *upd)
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{
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struct libmnt_table *tb;
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int rc = 0;
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assert(upd);
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assert(upd->fs);
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+ assert(upd->lock);
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DBG(UPDATE, ul_debugobj(upd, "%s: add entry", upd->filename));
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- if (lc)
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- rc = mnt_lock_file(lc);
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+ rc = mnt_lock_file(upd->lock);
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if (rc)
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return -MNT_ERR_LOCK;
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@@ -710,25 +712,24 @@ static int update_add_entry(struct libmnt_update *upd, struct libmnt_lock *lc)
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upd->userspace_only ? MNT_FMT_UTAB : MNT_FMT_MTAB, 1);
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if (tb)
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rc = add_file_entry(tb, upd);
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- if (lc)
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- mnt_unlock_file(lc);
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+ mnt_unlock_file(upd->lock);
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mnt_unref_table(tb);
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return rc;
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}
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-static int update_remove_entry(struct libmnt_update *upd, struct libmnt_lock *lc)
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+static int update_remove_entry(struct libmnt_update *upd)
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{
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struct libmnt_table *tb;
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int rc = 0;
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assert(upd);
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assert(upd->target);
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+ assert(upd->lock);
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DBG(UPDATE, ul_debugobj(upd, "%s: remove entry", upd->filename));
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- if (lc)
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- rc = mnt_lock_file(lc);
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+ rc = mnt_lock_file(upd->lock);
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if (rc)
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return -MNT_ERR_LOCK;
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@@ -741,23 +742,22 @@ static int update_remove_entry(struct libmnt_update *upd, struct libmnt_lock *lc
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rc = update_table(upd, tb);
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}
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}
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- if (lc)
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- mnt_unlock_file(lc);
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+ mnt_unlock_file(upd->lock);
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mnt_unref_table(tb);
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return rc;
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}
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-static int update_modify_target(struct libmnt_update *upd, struct libmnt_lock *lc)
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+static int update_modify_target(struct libmnt_update *upd)
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{
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struct libmnt_table *tb = NULL;
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int rc = 0;
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assert(upd);
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+ assert(upd->lock);
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DBG(UPDATE, ul_debugobj(upd, "%s: modify target", upd->filename));
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- if (lc)
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- rc = mnt_lock_file(lc);
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+ rc = mnt_lock_file(upd->lock);
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if (rc)
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return -MNT_ERR_LOCK;
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@@ -773,15 +773,13 @@ static int update_modify_target(struct libmnt_update *upd, struct libmnt_lock *l
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}
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}
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- if (lc)
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- mnt_unlock_file(lc);
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-
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+ mnt_unlock_file(upd->lock);
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mnt_unref_table(tb);
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return rc;
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}
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/* replaces option in the table entry by new options from @udp */
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-static int update_modify_options(struct libmnt_update *upd, struct libmnt_lock *lc)
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+static int update_modify_options(struct libmnt_update *upd)
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{
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struct libmnt_table *tb = NULL;
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int rc = 0;
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@@ -789,13 +787,13 @@ static int update_modify_options(struct libmnt_update *upd, struct libmnt_lock *
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assert(upd);
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assert(upd->fs);
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+ assert(upd->lock);
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DBG(UPDATE, ul_debugobj(upd, "%s: modify options", upd->filename));
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fs = upd->fs;
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- if (lc)
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- rc = mnt_lock_file(lc);
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+ rc = mnt_lock_file(upd->lock);
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if (rc)
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return -MNT_ERR_LOCK;
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@@ -816,15 +814,13 @@ static int update_modify_options(struct libmnt_update *upd, struct libmnt_lock *
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rc = add_file_entry(tb, upd); /* not found, add new */
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}
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- if (lc)
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- mnt_unlock_file(lc);
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-
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+ mnt_unlock_file(upd->lock);
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mnt_unref_table(tb);
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return rc;
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}
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/* add user options missing in the table entry by new options from @udp */
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-static int update_add_options(struct libmnt_update *upd, struct libmnt_lock *lc)
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+static int update_add_options(struct libmnt_update *upd)
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{
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struct libmnt_table *tb = NULL;
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int rc = 0;
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@@ -832,6 +828,7 @@ static int update_add_options(struct libmnt_update *upd, struct libmnt_lock *lc)
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assert(upd);
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assert(upd->fs);
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+ assert(upd->lock);
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if (!upd->fs->user_optstr)
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return 0;
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@@ -840,8 +837,7 @@ static int update_add_options(struct libmnt_update *upd, struct libmnt_lock *lc)
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fs = upd->fs;
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- if (lc)
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- rc = mnt_lock_file(lc);
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+ rc = mnt_lock_file(upd->lock);
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if (rc)
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return -MNT_ERR_LOCK;
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@@ -867,14 +863,33 @@ static int update_add_options(struct libmnt_update *upd, struct libmnt_lock *lc)
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rc = add_file_entry(tb, upd); /* not found, add new */
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}
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- if (lc)
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- mnt_unlock_file(lc);
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-
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+ mnt_unlock_file(upd->lock);
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mnt_unref_table(tb);
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return rc;
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}
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+static int update_init_lock(struct libmnt_update *upd, struct libmnt_lock *lc)
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+{
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+ assert(upd);
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+
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+ if (lc) {
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+ mnt_unref_lock(upd->lock);
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+ mnt_ref_lock(lc);
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+ upd->lock = lc;
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+ } else if (!upd->lock) {
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+ upd->lock = mnt_new_lock(upd->filename, 0);
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+ if (!upd->lock)
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+ return -ENOMEM;
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+ mnt_lock_block_signals(upd->lock, TRUE);
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+ }
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+
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+ if (upd->userspace_only)
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+ mnt_lock_use_simplelock(upd->lock, TRUE); /* use flock */
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+
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+ return 0;
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+}
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+
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/**
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* mnt_update_table:
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* @upd: update
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@@ -891,7 +906,6 @@ static int update_add_options(struct libmnt_update *upd, struct libmnt_lock *lc)
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*/
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int mnt_update_table(struct libmnt_update *upd, struct libmnt_lock *lc)
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{
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- struct libmnt_lock *lc0 = lc;
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int rc = -EINVAL;
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if (!upd || !upd->filename)
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@@ -903,37 +917,32 @@ int mnt_update_table(struct libmnt_update *upd, struct libmnt_lock *lc)
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if (upd->fs) {
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DBG(UPDATE, mnt_fs_print_debug(upd->fs, stderr));
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}
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- if (!lc) {
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- lc = mnt_new_lock(upd->filename, 0);
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- if (lc)
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- mnt_lock_block_signals(lc, TRUE);
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- }
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- if (lc && upd->userspace_only)
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- mnt_lock_use_simplelock(lc, TRUE); /* use flock */
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+
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+ rc = update_init_lock(upd, lc);
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+ if (rc)
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+ goto done;
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if (!upd->fs && upd->target)
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- rc = update_remove_entry(upd, lc); /* umount */
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+ rc = update_remove_entry(upd); /* umount */
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else if (upd->mountflags & MS_MOVE)
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- rc = update_modify_target(upd, lc); /* move */
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+ rc = update_modify_target(upd); /* move */
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else if (upd->mountflags & MS_REMOUNT)
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- rc = update_modify_options(upd, lc); /* remount */
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+ rc = update_modify_options(upd); /* remount */
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else if (upd->fs && upd->missing_options)
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- rc = update_add_options(upd, lc); /* mount by externel helper */
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+ rc = update_add_options(upd); /* mount by externel helper */
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else if (upd->fs)
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- rc = update_add_entry(upd, lc); /* mount */
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+ rc = update_add_entry(upd); /* mount */
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upd->ready = 1;
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+done:
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DBG(UPDATE, ul_debugobj(upd, "%s: update tab: done [rc=%d]",
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upd->filename, rc));
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- if (lc != lc0)
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- mnt_free_lock(lc);
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return rc;
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}
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-int mnt_update_already_done(struct libmnt_update *upd, struct libmnt_lock *lc)
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+int mnt_update_already_done(struct libmnt_update *upd)
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{
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struct libmnt_table *tb = NULL;
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- struct libmnt_lock *lc0 = lc;
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int rc = 0;
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if (!upd || !upd->filename || (!upd->fs && !upd->target))
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@@ -941,25 +950,8 @@ int mnt_update_already_done(struct libmnt_update *upd, struct libmnt_lock *lc)
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DBG(UPDATE, ul_debugobj(upd, "%s: checking for previous update", upd->filename));
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- if (!lc) {
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- lc = mnt_new_lock(upd->filename, 0);
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- if (lc)
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- mnt_lock_block_signals(lc, TRUE);
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- }
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- if (lc && upd->userspace_only)
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- mnt_lock_use_simplelock(lc, TRUE); /* use flock */
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- if (lc) {
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- rc = mnt_lock_file(lc);
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- if (rc) {
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- rc = -MNT_ERR_LOCK;
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- goto done;
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- }
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- }
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-
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tb = __mnt_new_table_from_file(upd->filename,
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upd->userspace_only ? MNT_FMT_UTAB : MNT_FMT_MTAB, 1);
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- if (lc)
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- mnt_unlock_file(lc);
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if (!tb)
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goto done;
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||
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|
@@ -996,8 +988,6 @@ int mnt_update_already_done(struct libmnt_update *upd, struct libmnt_lock *lc)
|
||
|
|
|
||
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|
mnt_unref_table(tb);
|
||
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|
done:
|
||
|
|
- if (lc && lc != lc0)
|
||
|
|
- mnt_free_lock(lc);
|
||
|
|
DBG(UPDATE, ul_debugobj(upd, "%s: previous update check done [rc=%d]",
|
||
|
|
upd->filename, rc));
|
||
|
|
return rc;
|
||
|
|
--
|
||
|
|
2.43.0
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||
|
|
|