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fd.c: Retry after EINTR in more places

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Starting with 4d330a61bb1 we can use posix_fallocate() to extend
files. Unfortunately in some situation, e.g. on tmpfs filesystems, EINTR may
be returned. See also 4518c798b2b.

To fix, add a retry path to FileFallocate(). In contrast to 4518c798b2b the
amount we extend by is limited and the extending may happen at a high
frequency, so disabling signals does not appear to be the correct path here.

Also add retry paths to other file operations currently lacking them (around
fdatasync(), fsync(), ftruncate(), posix_fadvise(), sync_file_range(),
truncate()) - they are all documented or have been observed to return EINTR.

Even though most of these functions used in the back branches, it does not
seem worth the risk to backpatch - outside of the new-to-16 case of
posix_fallocate() I am not aware of problem reports due to the lack of
retries.

Reported-by: Christoph Berg <myon@debian.org>
Discussion: https://postgr.es/m/ZEZDj1H61ryrmY9o@msg.df7cb.de
Backpatch: -
This commit is contained in:
Andres Freund 2023-06-19 14:11:32 -07:00
parent 797f980364
commit 0d369ac650
1 changed files with 61 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

73
src/backend/storage/file/fd.c
View File

@ -415,10 +415,18 @@ pg_fsync(int fd)
int
pg_fsync_no_writethrough(int fd)
{
if (enableFsync)
return fsync(fd);
else
int rc;
if (!enableFsync)
return 0;
retry:
rc = fsync(fd);
if (rc == -1 && errno == EINTR)
goto retry;
return rc;
}
/*
@ -448,10 +456,18 @@ pg_fsync_writethrough(int fd)
int
pg_fdatasync(int fd)
{
if (enableFsync)
return fdatasync(fd);
else
int rc;
if (!enableFsync)
return 0;
retry:
rc = fdatasync(fd);
if (rc == -1 && errno == EINTR)
goto retry;
return rc;
}
/*
@ -483,6 +499,7 @@ pg_flush_data(int fd, off_t offset, off_t nbytes)
if (not_implemented_by_kernel)
return;
retry:
/*
* sync_file_range(SYNC_FILE_RANGE_WRITE), currently linux specific,
* tells the OS that writeback for the specified blocks should be
@ -498,6 +515,9 @@ pg_flush_data(int fd, off_t offset, off_t nbytes)
{
int elevel;
if (rc == EINTR)
goto retry;
/*
* For systems that don't have an implementation of
* sync_file_range() such as Windows WSL, generate only one
@ -629,32 +649,54 @@ pg_flush_data(int fd, off_t offset, off_t nbytes)
#endif
}
/*
* Truncate an open file to a given length.
*/
static int
pg_ftruncate(int fd, off_t length)
{
int ret;
retry:
ret = ftruncate(fd, length);
if (ret == -1 && errno == EINTR)
goto retry;
return ret;
}
/*
* Truncate a file to a given length by name.
*/
int
pg_truncate(const char *path, off_t length)
{
int ret;
#ifdef WIN32
int save_errno;
int ret;
int fd;
fd = OpenTransientFile(path, O_RDWR | PG_BINARY);
if (fd >= 0)
{
ret = ftruncate(fd, length);
ret = pg_ftruncate(fd, length);
save_errno = errno;
CloseTransientFile(fd);
errno = save_errno;
}
else
ret = -1;
#else
retry:
ret = truncate(path, length);
if (ret == -1 && errno == EINTR)
goto retry;
#endif
return ret;
#else
return truncate(path, length);
#endif
}
/*
@ -2001,11 +2043,15 @@ FilePrefetch(File file, off_t offset, off_t amount, uint32 wait_event_info)
if (returnCode < 0)
return returnCode;
retry:
pgstat_report_wait_start(wait_event_info);
returnCode = posix_fadvise(VfdCache[file].fd, offset, amount,
POSIX_FADV_WILLNEED);
pgstat_report_wait_end();
if (returnCode == EINTR)
goto retry;
return returnCode;
#else
Assert(FileIsValid(file));
@ -2281,12 +2327,15 @@ FileFallocate(File file, off_t offset, off_t amount, uint32 wait_event_info)
if (returnCode < 0)
return -1;
retry:
pgstat_report_wait_start(wait_event_info);
returnCode = posix_fallocate(VfdCache[file].fd, offset, amount);
pgstat_report_wait_end();
if (returnCode == 0)
return 0;
else if (returnCode == EINTR)
goto retry;
/* for compatibility with %m printing etc */
errno = returnCode;
@ -2334,7 +2383,7 @@ FileTruncate(File file, off_t offset, uint32 wait_event_info)
return returnCode;
pgstat_report_wait_start(wait_event_info);
returnCode = ftruncate(VfdCache[file].fd, offset);
returnCode = pg_ftruncate(VfdCache[file].fd, offset);
pgstat_report_wait_end();
if (returnCode == 0 && VfdCache[file].fileSize > offset)