On 6/22/26 18:40, Jiucheng Xu wrote: > > On 6/22/2026 9:46 AM, Chao Yu wrote: >> [Some people who received this message don't often get email from >> [email protected]. Learn why this is important at https://aka.ms/ >> LearnAboutSenderIdentification ] >> >> [ EXTERNAL EMAIL ] >> >> On 6/20/26 17:34, Jiucheng Xu via B4 Relay wrote: >>> From: Jiucheng Xu <[email protected]> >>> >>> When continuous write operations occur in the system, BG GC fails to >>> work. This leads to large dirty_segments and small free_segments. If >>> fallocate() is performed on a pinned file with the allocated space >>> exceeding the free_segment, FG_GC reclamation fails. >>> >>> The reason is that the file corresponding to the block in the victim is >>> pinned, causing gc_data_segment() to fail. Since the condition sec_freed >> >> Jiucheng, >> >> pinned file should be aligned to section size, why there is fragmented blocks >> of pinfile locates in dirty sections? >> >>> < gc_control->nr_free_secs isn't satisfied, GC stops, resulting in the >>> failure of f2fs_fallocate() allocation. >>> >>> Setting gc_control->nr_free_secs = 1 make FG GC continue searching >>> for new victim. >> >> Maybe we can try this instead of changing f2fs_expand_inode_data() logic: >> 1. call fggc via ioctl or trigger urgent gc via sysfs >> 2. fallocate on pinfile, goto 1) if it failed >> >> But, anyway, I suspect it's risk, if there is no normal dirty section, >> FGGC will try to call f2fs_unpin_all_sections(), then migrate dirty section >> which has pinned blocks, that will cause more damage. >> >> Can you please figure out why pinfile is fragmented first... > > Hi Chao, > > Thanks for your feedback. I just do a test to simulate the Android OTA > createCowImage failed when dirty_segments is too large. > > Simple reproduction steps: > 1. In my case, dirty_segments=969, free_segments=96, free space = 1.7G, > section:segment = 1:1 > 2. touch a.bin > 3. f2fs_io pinfile set a.bin > 4. fallocate -l 1.5G a.bin > > And f2fs_fallocate() returns -11. > > Although the urgent mode work fine, but it is not very convenient to control > since AOPS has a great deal of code that calls fallocate. > > I have tried 5 times to fallocate(), but GC always selects the same victim > segno. So I think it is an issue. > > > The trace: > f2fs_get_victim: dev = (254,0), type = No TYPE, policy = (Foreground GC, > LFS-mode, Greedy), victim = 624, cost = 19... > > f2fs_gc_end: dev = (254,0), ret = 0, seg_freed = 0, sec_freed = 0, nodes = > 117, dents = 0, imeta = 98, free_sec:50, free_seg:50, rsv_seg:47, > prefree_seg:47 > > > I dump the failed victim segno, block offset in segment and related inode ino: > do_garbage_collect: ino=33902 segno=624 off=132 > > The dump of pinfile 33902 info: > main_blkaddr [0x 2600 : 9728] > i_inline [0x 61 : 97] > inline shows the file is pinned (0x60) > i_addr[0x9] [0x 2f7b2 : 194482] > i_addr[0xa] [0x 2f7b3 : 194483] > i_addr[0xb] [0x 2f7b4 : 194484] > ... > i_addr[0x1d] [0x 2f7c6 : 194502] > i_addr[0x1e] [0x 465af : 288175] > i_addr[0x1f] [0x 465b0 : 288176] > ... > i_addr[0x21] [0x 465b2 : 288178] > i_addr[0x22] [0x 5046d : 328813] > i_addr[0x23] [0x 5046e : 328814] > i_addr[0x24] [0x 505b6 : 329142] > i_addr[0x25] [0x 505b7 : 329143] > i_addr[0x26] [0x 505b8 : 329144] > i_addr[0x27] [0x 50684 : 329348] > i_addr[0x28] [0x 50685 : 329349] > > The file is created by logcat,and looks like indeed fragmented. > > Calculate the block address: > 624 * 512 + 132 + 9728(main_blkaddr) = 329348 > > So the i_addr[0x27] = 329348 is the failed block. > > Regarding "why the pinfile is fragmented" you said, we use v5.15 + android U. > Is it that v5.15 lacks some patches for special handling of pinfiles?
Ah, I think you can unpin log file created by logcat, the flag is added in aosp/1014260 to avoid fragmentation in filesystem (), but it's gone in aosp/43c6d76a Thanks, > > Thanks, > > >> >> Thanks, >> >>> >>> Signed-off-by: Jiucheng Xu <[email protected]> >>> --- >>> fs/f2fs/file.c | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c >>> index >>> 8acdd94272a0ced448e0ba21635d702cfec10682..3e49a73bbf3a184a314e97bff9509a66c27eac00 >>> 100644 >>> --- a/fs/f2fs/file.c >>> +++ b/fs/f2fs/file.c >>> @@ -1883,7 +1883,7 @@ static int f2fs_expand_inode_data(struct inode >>> *inode, loff_t offset, >>> .init_gc_type = FG_GC, >>> .should_migrate_blocks = false, >>> .err_gc_skipped = true, >>> - .nr_free_secs = 0 }; >>> + .nr_free_secs = 1 }; >>> pgoff_t pg_start, pg_end; >>> loff_t new_size; >>> loff_t off_end; >>> >>> --- >>> base-commit: b51f606aa323d553d786ed681a213f134dc688d6 >>> change-id: 20260620-origin-dev-99cdccc83800 >>> >>> Best regards, >> > _______________________________________________ Linux-f2fs-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
