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Use copy_file_range if available to allow COW filesystem optimization. #1

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Use copy_file_range if available to allow COW filesystem optimization. #1

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70 changes: 70 additions & 0 deletions src/backend/storage/file/copydir.c
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Original file line number Diff line number Diff line change
Expand Up @@ -19,13 +19,19 @@
#include "postgres.h"

#include <fcntl.h>
#include <sys/stat.h>
#include <unistd.h>

#include "common/file_utils.h"
#include "miscadmin.h"
#include "pgstat.h"
#include "storage/copydir.h"

#include <limits.h>
#include <common/logging.h>

#include "storage/fd.h"
#include "pg_config.h"

/*
* copydir: copy a directory
Expand Down Expand Up @@ -71,7 +77,11 @@ copydir(const char *fromdir, const char *todir, bool recurse)
copydir(fromfile, tofile, true);
}
else if (xlde_type == PGFILETYPE_REG)
#if defined(HAVE_COPY_FILE_RANGE)
copy_file_reflink(fromfile, tofile);
#else
copy_file(fromfile, tofile);
#endif
}
FreeDir(xldir);

Expand Down Expand Up @@ -214,3 +224,63 @@ copy_file(const char *fromfile, const char *tofile)

pfree(buffer);
}

/*
* copy one file using copy_file_range to give filesystem a chance to do COW optimization
*/
void
copy_file_reflink(const char *fromfile, const char *tofile)
{
#if defined(HAVE_COPY_FILE_RANGE)
int srcfd;
int dstfd;
ssize_t nbytes;

/*
* Open the files
*/
srcfd = OpenTransientFile(fromfile, O_RDONLY | PG_BINARY);

if (srcfd < 0)
ereport(ERROR,
errcode_for_file_access(),
errmsg("could not open file \"%s\": %m", fromfile));

dstfd = OpenTransientFile(tofile, O_RDWR | O_CREAT | O_EXCL | PG_BINARY);

if (dstfd < 0)
ereport(ERROR,
errcode_for_file_access(),
errmsg("could not create file \"%s\": %m", tofile));

/*
* Do the data copying.
*/
do
{
/* If we got a cancel signal during the copy of the file, quit */
CHECK_FOR_INTERRUPTS();

pgstat_report_wait_start(WAIT_EVENT_COPY_FILE_READ);
nbytes = copy_file_range(srcfd, NULL, dstfd, NULL, SSIZE_MAX, 0);
pgstat_report_wait_end();
if (nbytes < 0)
ereport(ERROR,
errcode_for_file_access(),
errmsg("could not copy file \"%s\": %m", fromfile));
}
while (nbytes > 0);

if (CloseTransientFile(dstfd) != 0)
ereport(ERROR,
errcode_for_file_access(),
errmsg("could not close file \"%s\": %m", tofile));

if (CloseTransientFile(srcfd) != 0)
ereport(ERROR,
errcode_for_file_access(),
errmsg("could not close file \"%s\": %m", fromfile));
#else
pg_fatal("copy_file_range not available on this platform");
#endif
}
1 change: 1 addition & 0 deletions src/include/storage/copydir.h
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Original file line number Diff line number Diff line change
Expand Up @@ -15,5 +15,6 @@

extern void copydir(const char *fromdir, const char *todir, bool recurse);
extern void copy_file(const char *fromfile, const char *tofile);
extern void copy_file_reflink(const char *fromfile, const char *tofile);

#endif /* COPYDIR_H */