Control: retitle -1 smbd: please "strict allocate" smarter than 1 byte at a time
On Mon, Oct 15, 2018 at 10:40:58PM +0200, Marcél Ströhle wrote: > When I initiate a samba share file transfer to a drive mounted through > MHDDFS, it takes many seconds to start writing, and I observe high MHDDFS > CPU usage. Reading a file works perfectly fine. Local writes are also fine. > The length of the delay seems to scale with the size of the file I want to > write. On Mon, Oct 15, 2018 at 11:57:26PM +0200, Marcél wrote: > I must have overlooked one setting in Samba when I was trying to eliminate > its configuration as a source for this issue: > strict allocate = yes > This seems to be what caused the problem. Sorry for the falsely attributed > bug report, but maybe it's interesting information - I still think it's > weird that this only caused an issue with FUSE/MHDDFS, not the other share > I was using. I can repro this on samba bookworm, reassigning appropriately. You only see this because syscalls to your other shares are infinitely faster (at least 3-20 times) than MHDDFS. On a Linux smbd mount, "truncate -s 100M 100M" by default (strict allocate = no) just works and makes a sparse file. With "strict allocate = yes", I see a busy-loop that looks like this mhddfs [2024-11-15 17:17:55] (info): [139671981946560] mhdd_write: /100M, handle = 139671732492784, count = 1, offset = 104759295 mhddfs [2024-11-15 17:17:55] (info): [139671963047616] mhdd_write: /100M, handle = 139671732492784, count = 1, offset = 104763391 mhddfs [2024-11-15 17:17:55] (info): [139671972497088] mhdd_write: /100M, handle = 139671732492784, count = 1, offset = 104767487 mhddfs [2024-11-15 17:17:55] (info): [139671981946560] mhdd_write: /100M, handle = 139671732492784, count = 1, offset = 104771583 mhddfs [2024-11-15 17:17:55] (info): [139671963047616] mhdd_write: /100M, handle = 139671732492784, count = 1, offset = 104775679 mhddfs [2024-11-15 17:17:55] (info): [139671972497088] mhdd_write: /100M, handle = 139671732492784, count = 1, offset = 104779775 mhddfs [2024-11-15 17:17:55] (info): [139671981946560] mhdd_write: /100M, handle = 139671732492784, count = 1, offset = 104783871 mhddfs [2024-11-15 17:17:55] (info): [139671963047616] mhdd_write: /100M, handle = 139671732492784, count = 1, offset = 104787967 mhddfs [2024-11-15 17:17:55] (info): [139671972497088] mhdd_write: /100M, handle = 139671732492784, count = 1, offset = 104792063 mhddfs [2024-11-15 17:17:55] (info): [139671981946560] mhdd_write: /100M, handle = 139671732492784, count = 1, offset = 104796159 mhddfs [2024-11-15 17:17:55] (info): [139671963047616] mhdd_write: /100M, handle = 139671732492784, count = 1, offset = 104800255 mhddfs [2024-11-15 17:17:55] (info): [139671972497088] mhdd_write: /100M, handle = 139671732492784, count = 1, offset = 104804351 mhddfs [2024-11-15 17:17:55] (info): [139671981946560] mhdd_write: /100M, handle = 139671732492784, count = 1, offset = 104808447 mhddfs [2024-11-15 17:17:55] (info): [139671963047616] mhdd_write: /100M, handle = 139671732492784, count = 1, offset = 104812543 mhddfs [2024-11-15 17:17:55] (info): [139671972497088] mhdd_write: /100M, handle = 139671732492784, count = 1, offset = 104816639 mhddfs [2024-11-15 17:17:55] (info): [139671981946560] mhdd_write: /100M, handle = 139671732492784, count = 1, offset = 104820735 mhddfs [2024-11-15 17:17:55]: [139671972497088] mhdd_getxattr: path = /home/nabijaczleweli/uwu/mhddfs/100Mc/100M name = security.capability bufsize = 0 mhddfs [2024-11-15 17:17:55] (info): [139671963047616] mhdd_write: /100M, handle = 139671732492784, count = 1, offset = 104824831 instead. And strace -fp "$(pgrep smbd)" shows [pid 3565208] pwrite64(28, "\0", 1, 103092223) = 1 [pid 3565208] pwrite64(28, "\0", 1, 103096319) = 1 [pid 3565208] pwrite64(28, "\0", 1, 103100415) = 1 [pid 3565208] pwrite64(28, "\0", 1, 103104511) = 1 [pid 3565208] pwrite64(28, "\0", 1, 103108607) = 1 [pid 3565208] pwrite64(28, "\0", 1, 103112703) = 1 [pid 3565208] pwrite64(28, "\0", 1, 103116799) = 1 [pid 3565208] pwrite64(28, "\0", 1, 103120895) = 1 [pid 3565208] pwrite64(28, "\0", 1, 103124991) = 1 [pid 3565208] pwrite64(28, "\0", 1, 103129087) = 1 [pid 3565208] pwrite64(28, "\0", 1, 103133183) = 1 [pid 3565208] pwrite64(28, "\0", 1, 103137279) = 1 [pid 3565208] pwrite64(28, "\0", 1, 103141375) = 1 [pid 3565208] pwrite64(28, "\0", 1, 103145471) = 1 [pid 3565208] pwrite64(28, "\0", 1, 103149567) = 1 [pid 3565208] pwrite64(28, "\0", 1, 103153663) = 1 [pid 3565208] pwrite64(28, "\0", 1, 103157759) = 1 [pid 3565208] pwrite64(28, "\0", 1, 103161855) = 1 [pid 3565208] pwrite64(28, "\0", 1, 103165951) = 1 [pid 3565208] pwrite64(28, "\0", 1, 103170047) = 1 [pid 3565208] pwrite64(28, "\0", 1, 103174143) = 1 [pid 3565208] pwrite64(28, "\0", 1, 103178239) = 1 [pid 3565208] pwrite64(28, "\0", 1, 103182335) = 1 [pid 3565208] pwrite64(28, "\0", 1, 103186431) = 1 [pid 3565208] pwrite64(28, "\0", 1, 103190527) = 1 [pid 3565208] pwrite64(28, "\0", 1, 103194623) = 1 [pid 3565208] pwrite64(28, "\0", 1, 103198719) = 1 [pid 3565208] pwrite64(28, "\0", 1, 103202815) = 1 [pid 3565208] pwrite64(28, "\0", 1, 103206911) = 1 [pid 3565208] pwrite64(28, "\0", 1, 103211007) = 1 [pid 3565208] pwrite64(28, "\0", 1, 103215103) = 1 [pid 3565208] pwrite64(28, "\0", 1, 103219199) = 1 [pid 3565208] pwrite64(28, "\0", 1, 103223295) = 1 [pid 3565208] pwrite64(28, "\0", 1, 103227391) = 1 [pid 3565208] pwrite64(28, "\0", 1, 103231487) = 1 [pid 3565208] pwrite64(28, "\0", 1, 103235583) = 1 [pid 3565208] pwrite64(28, "\0", 1, 103239679) = 1 [pid 3565208] pwrite64(28, "\0", 1, 103243775) = 1 [pid 3565208] pwrite64(28, "\0", 1, 103247871) = 1 [pid 3565208] pwrite64(28, "\0", 1, 103251967) = 1 [pid 3565208] pwrite64(28, "\0", 1, 103256063) = 1 [pid 3565208] pwrite64(28, "\0", 1, 103260159) = 1 There /has/ to be some smarter way to do this.
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