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   syncfs    ( 2 )

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Имя (Name)

sync, syncfs - commit filesystem caches to disk

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Синопсис (Synopsis)

#include <unistd.h>

       void sync(void);

       int syncfs(int fd);

   Feature Test Macro Requirements for glibc (see
   feature_test_macros(7)):

       sync():
           _XOPEN_SOURCE >= 500
               || /* Since glibc 2.19: */ _DEFAULT_SOURCE
               || /* Glibc <= 2.19: */ _BSD_SOURCE

       syncfs():
           _GNU_SOURCE

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Описание (Description)

sync() causes all pending modifications to filesystem metadata
       and cached file data to be written to the underlying filesystems.

       syncfs() is like sync(), but synchronizes just the filesystem
       containing file referred to by the open file descriptor fd.

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Возвращаемое значение (Return value)

syncfs() returns 0 on success; on error, it returns -1 and sets
       errno to indicate the error.

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Ошибки (Error)

sync() is always successful.

       syncfs() can fail for at least the following reasons:

       EBADF  fd is not a valid file descriptor.

       EIO    An error occurred during synchronization.  This error may
              relate to data written to any file on the filesystem, or
              on metadata related to the filesystem itself.

       ENOSPC Disk space was exhausted while synchronizing.

       ENOSPC, EDQUOT
              Data was written to a file on NFS or another filesystem
              which does not allocate space at the time of a write(2)
              system call, and some previous write failed due to
              insufficient storage space.

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Версии (Versions)

syncfs() first appeared in Linux 2.6.39; library support was
       added to glibc in version 2.14.

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Стандарты (Conforming to)

sync(): POSIX.1-2001, POSIX.1-2008, SVr4, 4.3BSD.

       syncfs() is Linux-specific.

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Примечание (Note)

Since glibc 2.2.2, the Linux prototype for sync() is as listed
       above, following the various standards.  In glibc 2.2.1 and
       earlier, it was "int sync(void)", and sync() always returned 0.

       According to the standard specification (e.g., POSIX.1-2001),
       sync() schedules the writes, but may return before the actual
       writing is done.  However Linux waits for I/O completions, and
       thus sync() or syncfs() provide the same guarantees as fsync()
       called on every file in the system or filesystem respectively.

       In mainline kernel versions prior to 5.8, syncfs() will fail only
       when passed a bad file descriptor (EBADF).  Since Linux 5.8,
       syncfs() will also report an error if one or more inodes failed
       to be written back since the last syncfs() call.

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Ошибки (баги) (Bugs)

Before version 1.3.20 Linux did not wait for I/O to complete
       before returning.

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Смотри также (See also)

sync(1), fdatasync(2), fsync(2)

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