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btrfs: send: check for read-only send root under critical section

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We're checking if the send root is read-only without being under the
protection of the root's root_item_lock spinlock, which is what protects
the root's flags when clearing the read-only flag, done at
btrfs_ioctl_subvol_setflags(). Furthermore, it should be done in the
same critical section that increments the root's send_in_progress counter,
as btrfs_ioctl_subvol_setflags() clears the read-only flag in the same
critical section that checks the counter's value.

So fix this by moving the read-only check under the critical section
delimited by the root's root_item_lock which also increments the root's
send_in_progress counter.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Filipe Manana 2024-11-06 11:26:07 +00:00 committed by David Sterba
parent dc058f5fda
commit e82c936293
1 changed files with 6 additions and 10 deletions
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16
fs/btrfs/send.c
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@ -8133,7 +8133,12 @@ long btrfs_ioctl_send(struct btrfs_inode *inode, const struct btrfs_ioctl_send_a
spin_unlock(&send_root->root_item_lock);
return -EPERM;
}
if (btrfs_root_readonly(send_root) && send_root->dedupe_in_progress) {
/* Userspace tools do the checks and warn the user if it's not RO. */
if (!btrfs_root_readonly(send_root)) {
spin_unlock(&send_root->root_item_lock);
return -EPERM;
}
if (send_root->dedupe_in_progress) {
dedupe_in_progress_warn(send_root);
spin_unlock(&send_root->root_item_lock);
return -EAGAIN;
@ -8141,15 +8146,6 @@ long btrfs_ioctl_send(struct btrfs_inode *inode, const struct btrfs_ioctl_send_a
send_root->send_in_progress++;
spin_unlock(&send_root->root_item_lock);
/*
* Userspace tools do the checks and warn the user if it's
* not RO.
*/
if (!btrfs_root_readonly(send_root)) {
ret = -EPERM;
goto out;
}
/*
* Check that we don't overflow at later allocations, we request
* clone_sources_count + 1 items, and compare to unsigned long inside