CVE-2026-68459: f2fs: fix potential deadlock in gc_merge path of f2fs_balance_fs()

In the Linux kernel, the following vulnerability has been resolved:

f2fs: fix potential deadlock in gcmerge path of f2fsbalancefs()

When we mount device w/ gcmerge mount option, we may suffer below potential deadlock:

Kworker GC trehad Truncator - f2fswritecachepages - f2fswritesingledatapage - f2fsdowritedatapage - foliostartwriteback --- set writeback flag on folio - f2fsoutplacewritedata : cached folio in internal bio cache - f2fsbalancefs - wakeup(gcthread) : wake up gc thread to run foreground GC - finishwait(fggcwq) : wait on the waitqueue --- wait on GC thread to finish the work - truncateinodepagesrange - filemapgetfolio(, FGPLOCK) --- lock folio - truncateinodepartialfolio - foliowaitwriteback --- wait on writeback being cleared - dogarbagecollect - movedatapage - f2fsgetlockdatafolio - lock on folio --- blocked on folio's lock

In order to avoid such deadlock, let's call below functions to commit cached bios in GCMERGE path of f2fsbalancefs() as the same as we did in NOGCMERGE path. - f2fssubmitmergedwrite(sbi, DATA); - f2fssubmitallmergedipuwrites(sbi);