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Fix handling of errors from dmu_write_uio_dbuf() on FreeBSD 

FreeBSD's implementation of zfs_uio_fault_move() returns EFAULT when a
page fault occurs while copying data in or out of user buffers.  The VFS
treats such errors specially and will retry the I/O operation (which may
have made some partial progress).

When the FreeBSD and Linux implementations of zfs_write() were merged,
the handling of errors from dmu_write_uio_dbuf() changed such that
EFAULT is not handled as a partial write.  For example, when appending
to a file, the z_size field of the znode is not updated after a partial
write resulting in EFAULT.

Restore the old handling of errors from dmu_write_uio_dbuf() to fix
this.  This should have no impact on Linux, which has special handling
for EFAULT already.

Reviewed-by: Andriy Gapon <avg@FreeBSD.org>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Signed-off-by: Mark Johnston <markj@FreeBSD.org>
Closes #12964
This commit is contained in:
Mark Johnston 2022-01-21 14:54:05 -05:00 committed by GitHub
parent 63a26454ba
commit 063daa8350
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 11 additions and 4 deletions
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15
module/zfs/zfs_vnops.c
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@ -338,7 +338,7 @@ out:
int
zfs_write(znode_t *zp, zfs_uio_t *uio, int ioflag, cred_t *cr)
{
int error = 0;
int error = 0, error1;
ssize_t start_resid = zfs_uio_resid(uio);
/*
@ -576,7 +576,11 @@ zfs_write(znode_t *zp, zfs_uio_t *uio, int ioflag, cred_t *cr)
continue;
}
#endif
if (error != 0) {
/*
* On FreeBSD, EFAULT should be propagated back to the
* VFS, which will handle faulting and will retry.
*/
if (error != 0 && error != EFAULT) {
dmu_tx_commit(tx);
break;
}
@ -660,7 +664,7 @@ zfs_write(znode_t *zp, zfs_uio_t *uio, int ioflag, cred_t *cr)
while ((end_size = zp->z_size) < zfs_uio_offset(uio)) {
(void) atomic_cas_64(&zp->z_size, end_size,
zfs_uio_offset(uio));
ASSERT(error == 0);
ASSERT(error == 0 || error == EFAULT);
}
/*
* If we are replaying and eof is non zero then force
@ -670,7 +674,10 @@ zfs_write(znode_t *zp, zfs_uio_t *uio, int ioflag, cred_t *cr)
if (zfsvfs->z_replay && zfsvfs->z_replay_eof != 0)
zp->z_size = zfsvfs->z_replay_eof;
error = sa_bulk_update(zp->z_sa_hdl, bulk, count, tx);
error1 = sa_bulk_update(zp->z_sa_hdl, bulk, count, tx);
if (error1 != 0)
/* Avoid clobbering EFAULT. */
error = error1;
zfs_log_write(zilog, tx, TX_WRITE, zp, woff, tx_bytes, ioflag,
NULL, NULL);