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9e2f9d34dd
syzbot reported a task hang issue due to a deadlock case where it is waiting for the folio lock of a cached folio that will be used for cache I/Os. After looking into the crafted fuzzed image, I found it's formed with several overlapped big pclusters as below: Ext: logical offset | length : physical offset | length 0: 0.. 16384 | 16384 : 151552.. 167936 | 16384 1: 16384.. 32768 | 16384 : 155648.. 172032 | 16384 2: 32768.. 49152 | 16384 : 537223168.. 537239552 | 16384 ... Here, extent 0/1 are physically overlapped although it's entirely _impossible_ for normal filesystem images generated by mkfs. First, managed folios containing compressed data will be marked as up-to-date and then unlocked immediately (unlike in-place folios) when compressed I/Os are complete. If physical blocks are not submitted in the incremental order, there should be separate BIOs to avoid dependency issues. However, the current code mis-arranges z_erofs_fill_bio_vec() and BIO submission which causes unexpected BIO waits. Second, managed folios will be connected to their own pclusters for efficient inter-queries. However, this is somewhat hard to implement easily if overlapped big pclusters exist. Again, these only appear in fuzzed images so let's simply fall back to temporary short-lived pages for correctness. Additionally, it justifies that referenced managed folios cannot be truncated for now and reverts part of commit |
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| .. | ||
| compress.h | ||
| data.c | ||
| decompressor_deflate.c | ||
| decompressor_lzma.c | ||
| decompressor_zstd.c | ||
| decompressor.c | ||
| dir.c | ||
| erofs_fs.h | ||
| fscache.c | ||
| inode.c | ||
| internal.h | ||
| Kconfig | ||
| Makefile | ||
| namei.c | ||
| super.c | ||
| sysfs.c | ||
| xattr.c | ||
| xattr.h | ||
| zdata.c | ||
| zmap.c | ||
| zutil.c | ||