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Fix history merge on all network file systems

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mmap() fails with ENODEV on remote file systems. This means we always fail
to read any old history on network file systems on Linux (except on the file
systems we recognize which are NFS, SMB and CIFS).

Untested, so I'm not sure if this works.

Fixes #10434
This commit is contained in:
Johannes Altmanninger 2024-10-08 10:49:18 +02:00
parent 37c04745e6
commit dc5823d150
1 changed files with 23 additions and 19 deletions
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42
src/history/file.rs
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@ -9,7 +9,7 @@ use std::{
time::{Duration, SystemTime, UNIX_EPOCH},
};
use libc::{mmap, munmap, MAP_ANONYMOUS, MAP_FAILED, MAP_PRIVATE, PROT_READ, PROT_WRITE};
use libc::{mmap, munmap, ENODEV, MAP_ANONYMOUS, MAP_FAILED, MAP_PRIVATE, PROT_READ, PROT_WRITE};
use super::{HistoryItem, PersistenceMode};
use crate::{
@ -45,18 +45,15 @@ impl MmapRegion {
/// Map a region `[0, len)` from an `fd`.
/// Returns [`None`] on failure.
pub fn map_file(fd: RawFd, len: usize) -> Option<Self> {
if len == 0 {
return None;
}
pub fn map_file(fd: RawFd, len: usize) -> std::io::Result<Self> {
assert!(len != 0);
let ptr = unsafe { mmap(std::ptr::null_mut(), len, PROT_READ, MAP_PRIVATE, fd, 0) };
if ptr == MAP_FAILED {
return None;
return Err(std::io::Error::last_os_error());
}
// SAFETY: mmap of `len` was successful and returned `ptr`
Some(unsafe { Self::new(ptr.cast(), len) })
Ok(unsafe { Self::new(ptr.cast(), len) })
}
/// Map anonymous memory of a given length.
@ -120,18 +117,25 @@ impl HistoryFileContents {
pub fn create(file: &mut File) -> Option<Self> {
// Check that the file is seekable, and its size.
let len: usize = file.seek(SeekFrom::End(0)).ok()?.try_into().ok()?;
let mmap_file_directly = should_mmap();
let mut region = if mmap_file_directly {
MmapRegion::map_file(file.as_raw_fd(), len)
} else {
MmapRegion::map_anon(len)
}?;
// If we mapped anonymous memory, we have to read from the file.
if !mmap_file_directly {
if len == 0 {
return None;
}
let map_anon = |file: &mut File, len: usize| {
let mut region = MmapRegion::map_anon(len)?;
// If we mapped anonymous memory, we have to read from the file.
file.seek(SeekFrom::Start(0)).ok()?;
read_zero_padded(&mut *file, region.as_mut()).ok()?;
}
Some(region)
};
let region = if should_mmap() {
match MmapRegion::map_file(file.as_raw_fd(), len) {
Ok(region) => region,
Err(err) if err.raw_os_error() == Some(ENODEV) => map_anon(file, len)?,
Err(_err) => return None,
}
} else {
map_anon(file, len)?
};
region.try_into().ok()
}
@ -216,7 +220,7 @@ fn should_mmap() -> bool {
}
// mmap only if we are known not-remote.
return path_get_config_remoteness() == DirRemoteness::local;
path_get_config_remoteness() != DirRemoteness::remote
}
/// Read from `fd` to fill `dest`, zeroing any unused space.