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vfs_vnops.c: Use va_bytes >= va_size hint to avoid SEEK_DATA/SEEKHOLE
vn_generic_copy_file_range() tries to maintain holes in file ranges being copied, using SEEK_DATA/SEEK_HOLE where possible, Unfortunately SEEK_DATA/SEEK_HOLE operations can take a long time under certain circumstances. Although it is not currently possible to know if a file has unallocated data regions, the case where va_bytes >= va_size is a strong hint that there are no unallocated data regions. This hint does not work well for file systems doing compression, but since it is only a hint, it is still useful. For the case of va_bytes >= va_size, avoid doing SEEK_DATA/SEEK_HOLE. Reviewed by: kib MFC after: 2 weeks Differential Revision: https://reviews.freebsd.org/D44509
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@ -3334,14 +3334,15 @@ vn_generic_copy_file_range(struct vnode *invp, off_t *inoffp,
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struct vnode *outvp, off_t *outoffp, size_t *lenp, unsigned int flags,
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struct ucred *incred, struct ucred *outcred, struct thread *fsize_td)
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{
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struct vattr inva;
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struct mount *mp;
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off_t startoff, endoff, xfer, xfer2;
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u_long blksize;
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int error, interrupted;
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bool cantseek, readzeros, eof, lastblock, holetoeof;
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bool cantseek, readzeros, eof, lastblock, holetoeof, sparse;
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ssize_t aresid, r = 0;
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size_t copylen, len, savlen;
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off_t insize, outsize;
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off_t outsize;
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char *dat;
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long holein, holeout;
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struct timespec curts, endts;
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@ -3357,11 +3358,26 @@ vn_generic_copy_file_range(struct vnode *invp, off_t *inoffp,
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goto out;
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if (VOP_PATHCONF(invp, _PC_MIN_HOLE_SIZE, &holein) != 0)
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holein = 0;
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error = vn_getsize_locked(invp, &insize, incred);
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error = VOP_GETATTR(invp, &inva, incred);
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if (error == 0 && inva.va_size > OFF_MAX)
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error = EFBIG;
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VOP_UNLOCK(invp);
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if (error != 0)
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goto out;
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/*
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* Use va_bytes >= va_size as a hint that the file does not have
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* sufficient holes to justify the overhead of doing FIOSEEKHOLE.
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* This hint does not work well for file systems doing compression
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* and may fail when allocations for extended attributes increases
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* the value of va_bytes to >= va_size.
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*/
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sparse = true;
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if (holein != 0 && inva.va_bytes >= inva.va_size) {
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holein = 0;
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sparse = false;
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}
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mp = NULL;
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error = vn_start_write(outvp, &mp, V_WAIT);
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if (error == 0)
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@ -3395,9 +3411,9 @@ vn_generic_copy_file_range(struct vnode *invp, off_t *inoffp,
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error = vn_getsize_locked(outvp, &outsize, outcred);
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if (error == 0 && outsize > *outoffp &&
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*outoffp <= OFF_MAX - len && outsize <= *outoffp + len &&
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*inoffp < insize &&
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*outoffp <= OFF_MAX - (insize - *inoffp) &&
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outsize <= *outoffp + (insize - *inoffp)) {
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*inoffp < inva.va_size &&
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*outoffp <= OFF_MAX - (inva.va_size - *inoffp) &&
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outsize <= *outoffp + (inva.va_size - *inoffp)) {
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#ifdef MAC
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error = mac_vnode_check_write(curthread->td_ucred,
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outcred, outvp);
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@ -3415,7 +3431,7 @@ vn_generic_copy_file_range(struct vnode *invp, off_t *inoffp,
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if (error != 0)
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goto out;
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if (holein == 0 && holeout > 0) {
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if (sparse && holein == 0 && holeout > 0) {
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/*
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* For this special case, the input data will be scanned
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* for blocks of all 0 bytes. For these blocks, the
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@ -3486,7 +3502,7 @@ vn_generic_copy_file_range(struct vnode *invp, off_t *inoffp,
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error = VOP_IOCTL(invp, FIOSEEKDATA, &startoff, 0,
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incred, curthread);
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if (error == ENXIO) {
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startoff = endoff = insize;
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startoff = endoff = inva.va_size;
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eof = holetoeof = true;
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error = 0;
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}
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@ -3549,6 +3565,8 @@ vn_generic_copy_file_range(struct vnode *invp, off_t *inoffp,
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cantseek = false;
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} else {
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cantseek = true;
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if (!sparse)
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cantseek = false;
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startoff = *inoffp;
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copylen = len;
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error = 0;
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