7925409e20
i_mutex on quota files is special. Unlike i_mutexes for other inodes it is acquired under dqonoff_mutex. Tell lockdep about this lock ranking. Also comment and code in quota_sync_sb() seem to be bogus (as i_mutex for quota file can be acquired under dqonoff_mutex). Move truncate_inode_pages() call under dqonoff_mutex and save some problems with races... Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
386 lines
8.9 KiB
C
386 lines
8.9 KiB
C
/*
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* Quota code necessary even when VFS quota support is not compiled
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* into the kernel. The interesting stuff is over in dquot.c, here
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* we have symbols for initial quotactl(2) handling, the sysctl(2)
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* variables, etc - things needed even when quota support disabled.
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*/
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#include <linux/fs.h>
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#include <linux/namei.h>
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#include <linux/slab.h>
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#include <asm/current.h>
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#include <asm/uaccess.h>
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#include <linux/kernel.h>
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#include <linux/security.h>
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#include <linux/syscalls.h>
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#include <linux/buffer_head.h>
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#include <linux/capability.h>
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#include <linux/quotaops.h>
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/* Check validity of generic quotactl commands */
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static int generic_quotactl_valid(struct super_block *sb, int type, int cmd, qid_t id)
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{
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if (type >= MAXQUOTAS)
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return -EINVAL;
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if (!sb && cmd != Q_SYNC)
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return -ENODEV;
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/* Is operation supported? */
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if (sb && !sb->s_qcop)
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return -ENOSYS;
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switch (cmd) {
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case Q_GETFMT:
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break;
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case Q_QUOTAON:
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if (!sb->s_qcop->quota_on)
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return -ENOSYS;
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break;
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case Q_QUOTAOFF:
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if (!sb->s_qcop->quota_off)
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return -ENOSYS;
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break;
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case Q_SETINFO:
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if (!sb->s_qcop->set_info)
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return -ENOSYS;
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break;
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case Q_GETINFO:
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if (!sb->s_qcop->get_info)
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return -ENOSYS;
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break;
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case Q_SETQUOTA:
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if (!sb->s_qcop->set_dqblk)
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return -ENOSYS;
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break;
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case Q_GETQUOTA:
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if (!sb->s_qcop->get_dqblk)
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return -ENOSYS;
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break;
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case Q_SYNC:
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if (sb && !sb->s_qcop->quota_sync)
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return -ENOSYS;
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break;
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default:
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return -EINVAL;
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}
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/* Is quota turned on for commands which need it? */
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switch (cmd) {
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case Q_GETFMT:
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case Q_GETINFO:
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case Q_QUOTAOFF:
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case Q_SETINFO:
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case Q_SETQUOTA:
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case Q_GETQUOTA:
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/* This is just informative test so we are satisfied without a lock */
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if (!sb_has_quota_enabled(sb, type))
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return -ESRCH;
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}
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/* Check privileges */
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if (cmd == Q_GETQUOTA) {
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if (((type == USRQUOTA && current->euid != id) ||
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(type == GRPQUOTA && !in_egroup_p(id))) &&
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!capable(CAP_SYS_ADMIN))
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return -EPERM;
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}
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else if (cmd != Q_GETFMT && cmd != Q_SYNC && cmd != Q_GETINFO)
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if (!capable(CAP_SYS_ADMIN))
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return -EPERM;
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return 0;
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}
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/* Check validity of XFS Quota Manager commands */
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static int xqm_quotactl_valid(struct super_block *sb, int type, int cmd, qid_t id)
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{
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if (type >= XQM_MAXQUOTAS)
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return -EINVAL;
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if (!sb)
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return -ENODEV;
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if (!sb->s_qcop)
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return -ENOSYS;
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switch (cmd) {
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case Q_XQUOTAON:
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case Q_XQUOTAOFF:
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case Q_XQUOTARM:
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if (!sb->s_qcop->set_xstate)
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return -ENOSYS;
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break;
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case Q_XGETQSTAT:
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if (!sb->s_qcop->get_xstate)
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return -ENOSYS;
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break;
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case Q_XSETQLIM:
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if (!sb->s_qcop->set_xquota)
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return -ENOSYS;
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break;
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case Q_XGETQUOTA:
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if (!sb->s_qcop->get_xquota)
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return -ENOSYS;
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break;
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case Q_XQUOTASYNC:
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if (!sb->s_qcop->quota_sync)
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return -ENOSYS;
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break;
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default:
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return -EINVAL;
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}
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/* Check privileges */
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if (cmd == Q_XGETQUOTA) {
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if (((type == XQM_USRQUOTA && current->euid != id) ||
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(type == XQM_GRPQUOTA && !in_egroup_p(id))) &&
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!capable(CAP_SYS_ADMIN))
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return -EPERM;
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} else if (cmd != Q_XGETQSTAT && cmd != Q_XQUOTASYNC) {
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if (!capable(CAP_SYS_ADMIN))
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return -EPERM;
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}
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return 0;
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}
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static int check_quotactl_valid(struct super_block *sb, int type, int cmd, qid_t id)
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{
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int error;
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if (XQM_COMMAND(cmd))
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error = xqm_quotactl_valid(sb, type, cmd, id);
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else
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error = generic_quotactl_valid(sb, type, cmd, id);
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if (!error)
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error = security_quotactl(cmd, type, id, sb);
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return error;
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}
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static void quota_sync_sb(struct super_block *sb, int type)
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{
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int cnt;
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sb->s_qcop->quota_sync(sb, type);
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/* This is not very clever (and fast) but currently I don't know about
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* any other simple way of getting quota data to disk and we must get
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* them there for userspace to be visible... */
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if (sb->s_op->sync_fs)
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sb->s_op->sync_fs(sb, 1);
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sync_blockdev(sb->s_bdev);
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/*
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* Now when everything is written we can discard the pagecache so
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* that userspace sees the changes.
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*/
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mutex_lock(&sb_dqopt(sb)->dqonoff_mutex);
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for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
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if (type != -1 && cnt != type)
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continue;
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if (!sb_has_quota_enabled(sb, cnt))
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continue;
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mutex_lock_nested(&sb_dqopt(sb)->files[cnt]->i_mutex, I_MUTEX_QUOTA);
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truncate_inode_pages(&sb_dqopt(sb)->files[cnt]->i_data, 0);
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mutex_unlock(&sb_dqopt(sb)->files[cnt]->i_mutex);
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}
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mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex);
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}
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void sync_dquots(struct super_block *sb, int type)
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{
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int cnt, dirty;
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if (sb) {
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if (sb->s_qcop->quota_sync)
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quota_sync_sb(sb, type);
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return;
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}
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spin_lock(&sb_lock);
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restart:
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list_for_each_entry(sb, &super_blocks, s_list) {
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/* This test just improves performance so it needn't be reliable... */
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for (cnt = 0, dirty = 0; cnt < MAXQUOTAS; cnt++)
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if ((type == cnt || type == -1) && sb_has_quota_enabled(sb, cnt)
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&& info_any_dirty(&sb_dqopt(sb)->info[cnt]))
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dirty = 1;
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if (!dirty)
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continue;
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sb->s_count++;
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spin_unlock(&sb_lock);
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down_read(&sb->s_umount);
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if (sb->s_root && sb->s_qcop->quota_sync)
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quota_sync_sb(sb, type);
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up_read(&sb->s_umount);
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spin_lock(&sb_lock);
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if (__put_super_and_need_restart(sb))
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goto restart;
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}
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spin_unlock(&sb_lock);
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}
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/* Copy parameters and call proper function */
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static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id, void __user *addr)
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{
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int ret;
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switch (cmd) {
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case Q_QUOTAON: {
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char *pathname;
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if (IS_ERR(pathname = getname(addr)))
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return PTR_ERR(pathname);
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ret = sb->s_qcop->quota_on(sb, type, id, pathname);
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putname(pathname);
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return ret;
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}
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case Q_QUOTAOFF:
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return sb->s_qcop->quota_off(sb, type);
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case Q_GETFMT: {
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__u32 fmt;
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down_read(&sb_dqopt(sb)->dqptr_sem);
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if (!sb_has_quota_enabled(sb, type)) {
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up_read(&sb_dqopt(sb)->dqptr_sem);
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return -ESRCH;
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}
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fmt = sb_dqopt(sb)->info[type].dqi_format->qf_fmt_id;
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up_read(&sb_dqopt(sb)->dqptr_sem);
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if (copy_to_user(addr, &fmt, sizeof(fmt)))
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return -EFAULT;
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return 0;
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}
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case Q_GETINFO: {
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struct if_dqinfo info;
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if ((ret = sb->s_qcop->get_info(sb, type, &info)))
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return ret;
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if (copy_to_user(addr, &info, sizeof(info)))
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return -EFAULT;
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return 0;
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}
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case Q_SETINFO: {
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struct if_dqinfo info;
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if (copy_from_user(&info, addr, sizeof(info)))
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return -EFAULT;
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return sb->s_qcop->set_info(sb, type, &info);
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}
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case Q_GETQUOTA: {
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struct if_dqblk idq;
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if ((ret = sb->s_qcop->get_dqblk(sb, type, id, &idq)))
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return ret;
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if (copy_to_user(addr, &idq, sizeof(idq)))
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return -EFAULT;
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return 0;
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}
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case Q_SETQUOTA: {
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struct if_dqblk idq;
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if (copy_from_user(&idq, addr, sizeof(idq)))
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return -EFAULT;
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return sb->s_qcop->set_dqblk(sb, type, id, &idq);
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}
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case Q_SYNC:
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sync_dquots(sb, type);
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return 0;
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case Q_XQUOTAON:
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case Q_XQUOTAOFF:
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case Q_XQUOTARM: {
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__u32 flags;
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if (copy_from_user(&flags, addr, sizeof(flags)))
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return -EFAULT;
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return sb->s_qcop->set_xstate(sb, flags, cmd);
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}
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case Q_XGETQSTAT: {
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struct fs_quota_stat fqs;
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if ((ret = sb->s_qcop->get_xstate(sb, &fqs)))
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return ret;
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if (copy_to_user(addr, &fqs, sizeof(fqs)))
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return -EFAULT;
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return 0;
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}
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case Q_XSETQLIM: {
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struct fs_disk_quota fdq;
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if (copy_from_user(&fdq, addr, sizeof(fdq)))
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return -EFAULT;
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return sb->s_qcop->set_xquota(sb, type, id, &fdq);
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}
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case Q_XGETQUOTA: {
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struct fs_disk_quota fdq;
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if ((ret = sb->s_qcop->get_xquota(sb, type, id, &fdq)))
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return ret;
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if (copy_to_user(addr, &fdq, sizeof(fdq)))
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return -EFAULT;
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return 0;
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}
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case Q_XQUOTASYNC:
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return sb->s_qcop->quota_sync(sb, type);
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/* We never reach here unless validity check is broken */
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default:
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BUG();
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}
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return 0;
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}
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/*
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* look up a superblock on which quota ops will be performed
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* - use the name of a block device to find the superblock thereon
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*/
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static inline struct super_block *quotactl_block(const char __user *special)
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{
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#ifdef CONFIG_BLOCK
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struct block_device *bdev;
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struct super_block *sb;
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char *tmp = getname(special);
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if (IS_ERR(tmp))
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return ERR_PTR(PTR_ERR(tmp));
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bdev = lookup_bdev(tmp);
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putname(tmp);
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if (IS_ERR(bdev))
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return ERR_PTR(PTR_ERR(bdev));
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sb = get_super(bdev);
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bdput(bdev);
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if (!sb)
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return ERR_PTR(-ENODEV);
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return sb;
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#else
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return ERR_PTR(-ENODEV);
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#endif
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}
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/*
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* This is the system call interface. This communicates with
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* the user-level programs. Currently this only supports diskquota
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* calls. Maybe we need to add the process quotas etc. in the future,
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* but we probably should use rlimits for that.
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*/
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asmlinkage long sys_quotactl(unsigned int cmd, const char __user *special, qid_t id, void __user *addr)
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{
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uint cmds, type;
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struct super_block *sb = NULL;
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int ret;
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cmds = cmd >> SUBCMDSHIFT;
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type = cmd & SUBCMDMASK;
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if (cmds != Q_SYNC || special) {
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sb = quotactl_block(special);
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if (IS_ERR(sb))
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return PTR_ERR(sb);
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}
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ret = check_quotactl_valid(sb, type, cmds, id);
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if (ret >= 0)
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ret = do_quotactl(sb, type, cmds, id, addr);
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if (sb)
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drop_super(sb);
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return ret;
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}
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